The render has a poor quality and is cut off at the bottom left.
The text is rough and uninteresting.
The background is a copy/paste.
All of that (except maybe the first point...) is absolutely fine because you just started out.
what you did right is the flow: the background "flows" diagonally from the bottom left corner to the top right one, just as the character's pose, thus the elements look better to the eye (try to flip the background... =P).
Aside that, i'd suggest you to "play with your render", thing you did already with the text but not enough: try to have the render in between other layers, having them interact with each other somehow.
Also, keep your text clean, little and visible: right now i'm unsure if i should focus on the render or on the text, just because of its size.
Lastly, take into consideration the rule of thirds(google it) and the quality of your resources.
About the subject of blending (aka "playing with your render" you could check an old work of mine, it does have some unsolved issues (for example the text) but IMO it shows well the blending.