TI’ll try again tomorrow. I’ll try again tomorrow.

Without a subject, it sounds like an instruction.

TI'll try again tomorrow. I'll try again tomorrow.

TI will try again tomorrow. I will try again tomorrow.

I have benen learnedstudying a lot of knowledgethings for a long time. I have been studying a lot of things for a long time.

I have benen learneding a lot of knowledge for a long time. I have been learning a lot for a long time.

I have benen learnedgaining a lot of knowledge in many different fields for a long time. I have been gaining a lot of knowledge in many different fields for a long time.

Or you can use what the other correctors wrote. This is just another way to write your sentence using "knowledge". It's hard to fix this sentence because we don't know what you have been learning, so I would suggest to add to this and say what exactly it is you have been gaining knowledge in.

I am so happy, I finally took the first step. I am so happy I finally took the first step.

I am so happy, I finally took the first step. I am so happy, I finally took the first step.

I am so happy, that I finally took the first step. I am so happy that I finally took the first step.

I would add more. By that I mean, you took the first step to what? Learn a new language?