Have a look in your neighbourhood, look in the stores. Check out your friendly web. Watch a George Michael video. At some point you will see something you like. Fiddle with it for a bit (for copyright reasons) and use the result.
If you are going to be more serious it will take a lot more work. Look up sites (or stores) about design and graphics. There are a lot of them about. You should be able to get an idea from them.
As for creating one for you, it would help if you explained what it is you are selling, which your focus group will be and what kind of impression you want to make. But ok, here's an idea:
, stolen from the web and modified. Try to choose your own colors that match the rest of your site.
