only thing I would like to say is add a lightsource and some more colours I think, cuzz its somewhat monotome, also make the dark a little lighter, cuzz to much negative is bad... and kill text, but pretty good text for a first anyways... you can make it a little lighter by adding a lighter blackish colour on a new layer with the bucket tool and then set it to lighten...

or you can apply image then do the following>image>layer Adjustments>exposure, then put them all a little to the right... hope that helps you a little...for colour editing, add gradient maps, selective colour adjustments or hue/saturate...