These aren't bad sigs. you need to work on a couple things though:
Text - in all of these sigs your biggest fall back is the text. They really stand out and are distracting. But keep working on it text is really hard to learn you'll get it eventually. ALso remember to use defeaults. A windows default text is going to be better than most texts you can download offline so to make it simple, keep 'em simple.
BG- your BG is pretty good on all of them, work on blending them to your render and making sure they work with the render.
Lighting - you need a light source, in the last naruto sig the light source would be to the left and top of the render. To make a light source, create a new layer - fill it black - set it to linear dodge - the select a bright color from the sig - and paint with a low opacity soft brush around 100 px. If ya need more help just ask.
Overall these are very good for a begginner but keep working.