idiot's guide to exporting iTunes to phone

[NoChatroomAtTheInn]

I'm trying to help my son get tunes onto his walkman phone. I've managed to suss CD to phone, but I can't make tunes purchased from iTunes go ont o the phone. It just says 'no usable files'.

I'm guessing this is a copyright issue?? But it might also be the other issue I have frequent difficulty with: namely the issue of my own total incompetance.

Can anyone shed light?? Pleeeese

Thanks v much justjules. I'll check out whether the phone can do mp4. Mumsnet always has an answer!

Anything bought from iTunes itself cannot be moved onto a phone.
They are 'locked' so can only be uses on iPods and the iPhone.
Anything that had been imported (cds you own) should be able to be transferred by looking up the folders in My Music (if you have windows) and moving them to the phone.

Thanks Elf.