ITunes music on harddrive

I have a lot of music CD's that I want to put into my iTunes, but I don't want to fill my SSD up with those files. I've also got a 1 TB external harddrive, which I have plugged into my Mac, which I'm sure could be used to help out, but I'm not sure how I would use iTunes to have the music loaded from the CD's, then placed on the external drive? How would I put it on the harddrive, and then how would ITunes access it? Would my music library then be split between the computer and the harddrive?

Thanks for any help.