The size doesn't make it look banner-ish. Make it wider and shorter. Also, the background looks too messy, pick up some tuts and you'll learn how to create a decent background.
Rather then adding an outer glow to the stock of Kankuro try blending him. To blend you simply select the eraser tool and choose a 100 pixel wide soft circle brush and lightly erase some of his outline.
Border's also help improve the overall look of your creation. To add a border press Ctrl+A then go to Edit>Stroke and type in 1 px and select the "Inside" option. After that set the color to black and click "OK".
The text is too small and the font doesn't suit it. Try going to Layer>Layer Style whilst the text layer is highlighted. It's pretty much self-explanatory.
Here's a list of fairly good tuts: http://www.gamerenders.com/forum/ind...owtopic=215891
That's fine for your first attempt. No worries! You'll inevitably improve just like the rest of us! ^^