this is my first wallpaper and i hope it ok, feedback please so i know what to improve on.

text doesnt fit so well try a different font, the render looks a bit big effects isnt good add work to it and blend it better, the texture work is really bad dont enlarge the texture it makes them look so bad, the colours are bad they dont fit, texture work that is put on it dont fit to well try using them better, background is bad improve it, keep practising kiu

Hmm its quit messy mate, try to keep it simple in the start.

The background needs to be more clean. Stock in the background should be more centered, with a dark background around it. Download some textures and add.
Render is a bit to big. Make it smaller, duplicate it and change the settings.
Font is okay, but could be better. The glow around it is not that good.
Maybe add some lightning work as well. Make a new layer and take a soft brush and make some spots.

Keep practising and take a look in the tutorial section.