ot abd ur backgorun dont look half bad..i would jus say maybe try to make the backgorun so it sorta matches ..even though it dotn match but..as long as it dont clash with ur rende.r.Try blending the guy in a lil and maybe use a beter render coz the qality seems a bit low...nice try.
For a first its not bad. BG isnt too bad looks a little pixalted. Render would flow if colors matched. Black splots not needed. Overall : For a first u have a decent idea.
