I love making Twitter backgrounds and you can too! If you follow me on twitter then you know that I frequently change my background. It’s really fairly easy as long as you have Photoshop or some other type of paint type of software. I think its really important to have one so that when people visit your Twitter page they can instantly know what you are all about at a glance. If you are into painting maybe create a background with some of your artwork along with a photo of yourself and then create a longer bio than what Twitter allows on the left hand side. You would be surprised how many more people will follow you once you do this.
When you make your background you’ll notice that it looks different on different screens. That is because people have different resolutions. What I typically will do is start with my document layout as 1280×800 pixels and then check it on different screens. If you don’t have the convenience of having different screens available to look at it ask someone with a different screen how it looks and where things are cutting off. As an FYI, Twitters screen is 736 and the logo for Twitter is 71 pixels (roughly). The Twitter logo is going to be at the top left side of your design so remember that as you make your design.
To get the design into your profile, go to settings, design and choose browse to get to your file. Click save and voila! Below are a few designs I have made (click to enlarge). I usually create the right side as a double column for the different screen sizes or you can use one large image.