It's in the Owners' Manual, and it depends on what you are trying to do.

You can upload directly from CD's by simply putting them in the CD/DVD slot and using the idrive to tell it to upload the CD.

You can make a back-up DVD from itunes, put the DVD in the CD/DVD drive, and tell it to upload the songs (but it will not upload copy-protected songs purchased from the itunes store).

You can also do it from a memory stick, but I've never tried that.

I suggest you:

(a) Take a look at the Owner's Manual, and

(b) Post what you are specifically trying to do, e.g., the source of the songs you want to upload.