With your stereo powered on, press and hold the '4' key. This will get you into the menu system, you can use the 'am' and 'fm' keys to scroll through all the different options. There are 3 main display types, A, B, and C. Display type A and B let you show song information, and station information and the clock if you want. Type C is the full-motion screensavers and generally crap that makes me dizzy. Once you pick a type, you can setup the information you want displayed. Type B is very simple, type A is more info and some graphics, and type C is all graphics and basically no info.
Anyway, the manual in your glove box explains it all pretty well. I spent my entire first night reading through the manual. Once you get into the menu system for our head-units, you'll realize just how much there is you can configure, so it's best to use the manual the first couple of times until you get it down.
As for the MP3 files themselves, the files do need to have ID3 version 1.0 or 1.1 tags. I discovered the really small mention of this in the manual after my first MP3 cd kept displaying 'No Data' for every song. I use iTunes on my mac, so it's super easy for me to convert my newer (v.2.x) tags into 1.x tags, I'm sure there's some way to do it easily on a PC as well, check your MP3 software. Any software that is designed to work with an MP3 player such as an iPod or RIO will probably have a way to convert tags since some of those devices are also finicky about ID3 tags.