It's actually good for a first try. I use a plain, suckish background for my first one, so yours is much better. lol.
I think that the pokemon is kind of the same color compared to the background, which makes it hard to see. Make the picture you're using darker or lighter than the background. For the background, it's kind of plain. I suggest that you use two to three textures for the background rather than one. You also wouldn't want to put the picture you're using in the banner too close to the text, unless you're actually trying to overlap it. The border trick is a cool thing to do.