I do many things on my free time.
The things I like to do are reading books, watching TV and playing the piano .
The thing I don't like to do is studying on my free time.
I think spending my time doing the things I like to do is very good.

Thank you for doing your homework!
REMINDERS:
* Always capitalize I and the word TV.

* Be mindful of the use of AND. We used it to join words phrases or parts of sentences.

* We used THE before the names of musical instruments.
Example: I can play the violin.

* A singular subject takes a singular verb while a plural subject takes a plural verb.
- The things I like to do are ..
- The thing I don't like to do is ..

I revised your sentence to make it clear. ~> I think spending my time doing the things I like to do is very good.

Start your day with a smile. Happy Monday!