Mac question

This might be helpful: Adding content on your computer to iTunes

I assume its a USB drive. The first thing I would do is try a different USB port. There may be a problem with the one you are using. After that, try rebooting your computer with the drive already in place. If it still doesn't work, ask your friend what file system he formatted the drive with and what format is the music in. It may not be compatible with Mac OS.

There are some other things you can try, but I would do this first.

With the thumb drive installed, Open iTunes, in the upper left hand corner of the screen is the word "iTunes", just to the right of it is the word "File". open the drop down menu. listed on the menu is "Add To Library". click it. a finder type window will appear. If the thumb drive is active it will be located in the left of the window, click it. any files on the drive should appear. select the folder or folders you want and click open. the music files will be added to your iTunes.

Good luck.

Ejlif is correct - you have to go through iTunes on a Mac. You can use a different program to burn a CD of stuff you like (I use a program called Burn), but iTunes has to see it first before you can do anything else with it.

I understand the need to go through iTunes to access the music (if he's using iTunes as his player), but you should still be able to see the files themselves in finder. That's why I think the issue may lie elsewhere.