Hi, I have a question, hope you guys help me.

I want to know how can i paste a texture under my picture like this one?


whenever i paste my texture under the pic, i try to clean the extra parts with magic erase or losso tool, but it looks that i cleaned those part so bad and it looks so weird.
anyone can help me?


and i'm sorry to the person who've made that ava, 'cause i forgot.