Oh cool, art topic!
I'd recommend using Photoshop if you have it. If you don't, I think you can DL the trial =I think>.>=, or use Paint.NET (free), GIMP (free, I think), Easy Paint Tool Sai (arguably freeXD), OpenCanvas etc.
If you are an artist, you could always draw a picture, if not, depending on your game, try to google some generic wallpapers. Try searching for some nature stuff?(It really DOES depend on your game).
Then get some cool fonts, from dafont.com or anywhere else on google (It's your best friend)
When using fonts, make sure the edges are anti-aliased, it makes it look smoother, and try not to use solid or gaudy colors. Find colors that match the whole image.
A logo would be nice.
All of the programs I recommended use layers, so make use of them.
If you dont really know how to use layers, try to find a photoshop tutorial
on them, they are basically the same throughout all programs that use layers.
To make your letters look shiny *I assume you mean a chrome effect?* depending on your program, you can add that effect somehow... I know that Sai doesn't have that effect, but Photoshop does, in the filter tab.
Lol I have a feeling that this doesn't really help much, but I like to contribute 8D