My weekend

I spent my weekend very well [it sounds more natural to say "I had a very good weekend"]. I was only at home [do you mean "I was at home alone"? "Only at home" means "at home and nowhere else"]. That's why because I was ill. It was boring for me. I went to the library with my friend at the weekend. We chose decided to read some books. Then we went for a walk. The weather was very fine nice ["very fine" sounds strange to English ears, some adjectives don-t go well with "very"]. That's why I was in a good mood. We had a good time together.

My weekend

I spent my weekend very well. I was only at home, that's why I was ill. It was boring for me. I went to the library with my friend over the weekend. We chose to read some books, then we went for a walk. The weather was very fine. That's why I was in a good mood. We had a good time together.

-When referring to something we did last the weekend, we say "over the weekend", not "at the weekend"

-Hmm. Were you really ill because you were home, or home because you were ill?

-Combine some sentences with a comma to add variety to the sentence rhythm :)