When you say you added a "background" do you mean you installed a Wallpaper package? If so, those are likely not compatible with the iPad at all. Remember, Cydia has been around for many years, and it contains packages dating back to the original iPhone. Back in those days there was no wallpaper function in IOS, so jailbreaking allowed you to add backgrounds. These will certainly not work properly now, and will never work on an iPad.
A very large percentage of packages in Cydia are not designed for iPad. You need to carefully look at the descriptions of things before you install them to see if they are designed for our devices.
If you simply want a new background, use the built in Wallpaper function. There are plenty of websites, and of course good old google, where you can source a huge selection of wallpapers.
If you are talking about full Themes for the iPad, again you need to make sure the themes are iPad specific. Have a look in our Themes sub-section to see a good selection of the best ones which are for our devices.
Good luck!
PS - I'm just checking, when you say iPod 2, you mean iPad 2 right? If you actually mean the second generation iPod then I'm not going to be able to help too much. The last time I jailbroke a 2G iPod was bout 5 years ago when I put linux on it!
Since Cydia doesn't work on an iPod2G, I'm pretty sure you mean iPad
