How can I listen to my iTunes music on my IPAD without a wireless signal?

I have an ipad, version 4.2.1. Why can't I listen to the itunes songs I put into the ipad when I don't have a wireless signal? I can't advance past the "itunes store" screen. I synced it to my iMac, running 10.6.5. All the songs are there. I do not have wireless at home, nor do I plan on getting it. Is there a way to listen to my itunes music in Airplane mode? Also, at my job at a middle school, the ipad is much worse at finding our wireless signal than our Macbooks are. Any ideas?