I just signed up and (am) not sure how to use this site.

I think "am" makes it sound a little bit more natural.

It's heard the sad news that Lang-8 will be terminatedshut down in three months.

I hope I will have friends here soon so we cand help each other.

I've usedd been using Lang-8 for 14 years.

If I say "I've used the same phone charger for a year, now," even though "used" is in past tense, the statement does not imply that I intend to switch to another charger. This is because "I have used" refers to present actions compared to "I used to" which is for past actions. Changing "I've used" to "I had been using" has this nuance of the end to this behavior being recent.

It's sad news that Lang-8 will be terminatedshut down in three months.

I just signed up and noam not yet sure how to use this site.

You can also substitute "and" for "though" here. The nuance is hard to explain.

I feel like without the "yet" here, it's maybe a bit like the difference between 知らない and わからない in that it can come across as not caring or feeling the need to understand. I can say for myself, I do not understand TikTok, nor do I care to. But to speak of Japanese, I do not *yet* understand it.

I hope I will have friends here soon and we can help each other.

It's sad news that Lang-8 will be terminatedshut down in three months.

"Terminated" sounds too formal to use in the context of a website, and "terminated" is used more often in contexts like the workplace (for example, "His contract was terminated last month"). "Shut down" and "end" are more common and natural to use when talking about a website.

I just signed up, and I'm not sure how to use this site.

I hope I will have friends here soon and we can help each other.