hi, somebody wants practice english with me?
The Duolingo forums aren't great for finding language exchange partners. It can be worth posting in the individual language forums, but even then, you rely on someone happening to be looking for a language exchange partner at the same time as you. Have a look at this post about how to find language exchange partners: https://www.duolingo.com/comment/1444346.
There are sites dedicated to putting language learners in touch with each others. Have a look at the list of language exchange sites on the Multilingual learning resources page on the Duolingo Wiki.
Sure! When you're asking a question, you either say 'do you' or 'does'. I'm sure you know it's 'he does', right? Well, here you're asking if somebody wants to practice with you. Somebody takes the place of 'does he want to practice'. It might seem a bit confusing at first. And it is 'want to' because 'to do' has already been conjugated in the sentence. Does that make sense?
Edit: you're title would be a statement that somebody wants to practice English with you, plus a question mark.