It's absolutely great for a first timer, I couldn't even made something like that at my first poster making otl. Although you could've tried to soft blend the boy character instead of hard erasing it and the girl character seemed to be fading into the background (But if the girl is some kind of a spirit or ghost then it's fine). The stock too, I still can see the edges :) maybe you can try to fixed it by blending it again. Next time you make again, try to put more stocks and textures to enhance your poster/graphics and try to put some psd colorings(if you used photoshop).

I talked too much ;; otl. Overall! It's awesome for beginner, keep it up! And I hope you'll find my advice useful ^^