Q: I have recently purchased a MacBook Air. Without buying an external CD drive, how can i get my songs from my CD's to my Mac iTunes?

If they’re in a computer’s iTunes library, you can move that library to the MacBook Air by using an external drive or network.

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It will only erase your iPod if you did not transfer your library from your old computer (or its backup) to your new one first.  If you didn't do that first I figure a plain, regular external optical drive (vs. Apple's "Super" drive) will cost only a bit more than the software you would have to buy to get them off your iPod.

More details can be provided but right now the scenario is too open-ended.  Do you still have your old computer?

Locate the iTunes library on the old computer.

1. If you choose to use a network, start File Sharing, navigate to the Music folder in your home folder on the MacBook Air, and drag the library over.

2. If you choose to use an external hard drive, drag it to the drive, unplug the drive, connect it to the MacBook Air, and drag the library to the Music folder in your home folder.

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If you still have your ld computer, the easiest thing to do will be to transfer the library from it to the new computer.

How to move your iTunes library to a new computer - Apple Support

Depending on how large your library is, a USB drive may be enough.

Otherwise, a Network transfer may take longer, but will not require any external hardware other than your wifi network.

iTunes 11 for Mac: Use Home Sharing to import items from another iTunes library

Yes.