I decided to start a job hunting.

"Job hunting" is a verb, not a noun

Upon dorealizing this, I first filled up my lLinkedin profile, which I left it blank for almost two months after I' had created the account.

"Realizing" is the best word for a conclusion. "Upon realizing this conclusion" basically
You referred to the Linkedin profile already, so you don't need "it"
"had created" because it happened before another past action

There, I have only severalonly have a (few/couple) connections that I made whilen taking an online university course, and for the first time I. I also read the timeline carefully, being for the first time since opening an account, since I was curious onabout what's going on in the job hunting world.

"several" does not have the connotation that it is very little. "A few" and "a couple" gives the feeling of insufficiency

I'm confused on what "the first time" is relative to. The first time since you created your account?

Curious about something, not on something

Soon I noticed that lLinkedin wasn't for me as it figurespromoted recruitment posts from a lot of foreign companies' recruitement posts.

You can move the "recruitment posts" before "foreign companies" to focus on the object

I'm not interested in working for foregign companies, even though they areones based in Japan, asince their recruitement system is a lot different from that of Japan's.

I assume not all the foreign companies were based in Japan, so if you are only talking about ones that are: "even ones based in Japan."

In my opinion, Japanese people tend to have a very peculiear attitude with regards to anything related to work compared to the rest of the world, and unfortunately I'm more used to the Japanese culture.

Theere I realized another thing: my friends on lLinkedin shared the information of job huntingir job hunting information with each other.

I've seen this kind of custom in the IT industry in Japan, but not in other dcomainsmunities (?).

Not sure what "domain" means. Websites? Other platforms/communities?

But here, Kkeeping in touch with others, exchanging information, getting a help ofrom others and helping others in return etc...these are the common practices and also the very reasons why theypeople are on lLinkedin.

Getting help "from" others
Also clarify what "they" refer to, because it is not the actions that are on Linkedin, it is people who do these things using Linkedin.

Now I felt like understanding why this business social network website is so popular and is experience a user increing a growth in their user base.

You understand the sentiment now, so you can use present tense
Linkedin is experiencing a growth right now -> present tense
Growth means expansion, so it would be a better word
User base is a general term for the number of users. "Number of users" can also work if you're talking about "increasing"

I decided to start a job hunting.

I can not relatdescribe this matter in detail here, but with many conditions consideredafter considering many options, my husband and I reached a conclusion that it is the best thing to do.

Upon doing this, I first filled upout my linkedin profile, which I had left it blank for almost two months after I'd created the account.

"fill" + out

Soon I noticed that lLinkedin wasn't for me as it figurincludes a lot of foreign companies' recruitement posts.

I'm not interested in working for foregign companies, even though they are based in Japan, as their recruitement system is a lot different from that of Japan.

In my opinion, Japanese people tend to have a very peculiear attitude within regards to anything related to work compared to the rest of the world, and unfortunately I'm more used to the Japanese culture.

I understand!

Now I felt like understanding why this business social network website is so popular and experiences a user increase.

I decided to start a job hunting.

I can not relate this matter in detail here, but with many conditions, after much consideredation, my husband and I reached athe conclusion that it is the best thing to do.

Upon doeciding this, I first filled upout my linkedin profile, which I had left it blank for almost two months after I'd created the account.

There, I have only several connections that I made when taking an online university course, and, for the first time I read the timeline carefully, beingcause I was curious onabout what's going on in the job hunting world.

Soon I noticed that linkedin wasn't for me as it figuresdisplayed a lot of foreign companies' recruitement postrecruitment posts by foreign companies.

I'm not interested in working for foregign companies, even though they are based in Japan, as their recruitement system is a lot different from that of Japan.

In my opinion, Japanese people tend to have a very peculiear attitude with regard to anything related to work compared to the rest of the world, and, unfortunately, I'm more used to the Japanese culture.

Theeren I realized another thing: my friends on linkedin shared the information ofabout job hunting with each other.

I've seen this kind of custom in the IT industry in Japan, but not in other domains.

But here, Kkeeping in touch with others, exchanging information, getting a help ofrom others and helping others in return, etc...these are the common practices now and also the very reasons why they are on linkedin.

Now I felt likeas if I understandingood why this business social network website is so popular and experienced a usern increase in users.

Upon doing this, I first filled upin my linkedin profile, which I had left it blank for almost two months after I'd created the account.

There, I have only several connections that I made when taking an online university course, and for the first time I read the timeline carefully, being curious onabout what's going on in the job hunting world.

Soon I noticed that linkedin wasn't for me as it figurincludes a lot of foreign companies' recruitement posts.

AThe set of implicit rules for business practices also differs extensively, which would make it difficult for me to adjust to the culture of a foreign company.

In my opinion, Japanese people tend to have a very peculiear attitude with regard to anything related to work compared to the rest of the world, and unfortunately I'm more used to the Japanese culture.

Theere I realized another thing: my friends on linkedin shared the information ofabout job hunting with each other.

I've seen this kind of custom in the IT industry in Japan, but not in other domains.

But here, Kkeeping in touch with others, exchanging information, getting athe help of others and helping others in return etc...these are th are common practices, and also the very reasons why they are on linkedin.

Now I felt like I understandingood why this business social network website is so popular, and experienced a user increase.

I think this is you explaining why you now understand about LinkedIn. Alternatively, if this experience has made you _want_ to learn more about LinkedIn, then you might say "Now I feel like understanding more about why this business social network website is so popular and is experiencing a user increase."