ou need to purchase and install Pwntunes and Safari Download. Both are well worth the price and can be found in Cydia.
Once you have the apps downloaded and installed, open safari and go to either
http://www.beemp3.com or you can google the song you want to download directly.
Safari download manager will pop up and you will want to make sure to select download to. Then hit the media button to go back, scroll down and select My Music and then hit save.
Once the song has downloaded, go into setting and scroll down to Pwntunes and turn Needs Sync to On, and open up your ipod app and the music will then import and that is it.