STUDENT'S HOMEWORK
I like swim
It a swimming pool

TEACHER'S CORRECTION
I like to swim.
It's a swimming pool

TEACHER'S EXPLANATION
1. Don't forget to put a prepositions in your sentence so that your reader can easily  understand the thought of your sentence. "To" is the  preposition that we used in your example number 1.
2. "Is' a very important in a sentence. We use "is when a subject is singular and "are" when plural.

TEACHER'S NOTE:
Hi Peter! I appreciate your assignment and thank you so much for doing that. Please be aware on my corrections in your sentence. Don't worry  little  by little you can understand those things, but as of now let's just focus first  on our conversation so that you can improve  that skills. Thank You Peter! T. Bernard