Wat do you do when the itunes asks you to use the AC adapter.?

the itune told me that the ipod wasn't fomatted. It was fomatted for Macintosh... So I formmated it. Then the itunes told me that I just need to connect the ipod to the AC adapter. But I dont have one. What should I do? Every time I plug it in it shows a picture of the ipod and AC... pluging in. Pleas help