"I'm a girl who likes" or "I'm a girl who like"? I am confused with these two. Is it "I am a girl who likes" -- 'likes' follows the word 'a girl' or "I am a girl who like" -- 'like' follows the word "I"? Thanks before!

"I think it better" or "I think it's better"? I find these two sentences often on the internet at the same time. Which one is right, "I think it better" or "I think it's better"? Thanks before!