Just a notebook entry.

It has been a long time since I wanted to write a notebook entry, but I did not know about what I must write.

You will not believe this: In terrible, hot weather, I got the flu. I could not fall asleep and decided to enter italki. I wrote a comment in one of the discussions. My comment was about love. I wrote what I thought, but sometimes I feel that people interpret other people's comments in the wrong way. Do not do it. If you do not agree, then write your opinions, ask questions. Do not forget that we take part in discussion so we can discuss some thoughts, some questions.
Take care. Do not be ill to others.

Just a notebook entry.

It is been a long time since I wanted to write a notebook entry.

It has been a long time since ...

But I did not know what about I must write.

But I did not know what [   ] I should write about.

You will not believe.In terrible hot weather I got a flu.And I could not to sleep and desided to enter italki.

You won't believe what happened.  In terrible hot weather, I got the flu. And I could not [  ] sleep and decided to logon/log-on to italki.

I wrote a comment in one of the discussions. My comment was about love.I wrote what I thought.But sometimes I feel that people imagine the other's comments in wrong way.

But sometimes I feel that people take other people's comments the wrong way.

But sometimes I think that people take other people's comments the wrong way.

But sometimes I think that people's comments are taken the wrong way.

Do not do it.If you do not agree, write your opinions, ask questions.Do not forget we take part in discussion where we can discuss some thoughts, some questions.

If you do not agree (with what someone has written(?)), write your (own) opinions, ask questions. 

Take care. Do not be ill.

Take care.  Be well.

Note:

Don't sounds more natural. 

"Do not" isn't wrong, but it's rather formal and sounds "forceful"

Remember to put spaces after punctuation and the words that follow.

This sentence is correct.  This sentences is correct, too. 

This sentences is incorrect.Because there's no space after the period and before the "because".