Yes, it's pretty detailed. For adding a background image in 11.04, Grub2 makes it pretty easy. Here is a guide I wrote about Grub 1.99 and backgrounds:
Originally Posted by larrivee013
It may also look a bit complicated, especially the fonts section, but essentially you just drop an image file into /boot/grub.
As far as the error message - it could mean the package has a serious problem, but it could also be a minor bug. I generally take the advice of what Ubuntu tells me. You could do a search to see if others are having problems installing the package. Depending on your risk tolerance, you could download the .deb file (or it may already be in your /var/cache/apt/archives folder) and install it using:
sudo dpkg -i /path/filename.deb