If you want to do it manually, you can always use iTunes.
That's all I did with some of my really old albums which had all sorts of filenames and no id3 tags.
I setup iTunes to copy everything I import to the itunes library folder. It also renamed the files to the names you set.
Then import the files (drag+drop), select them all and click on "get info" You get a dialog saying about editing multiple files, click yes and just edit the album name etc, clicking the check box to apply to all selected items.
I'm sure there was a program that did ID3 tags from CDDB tho, can't remember if it was a apple thing or windows thing tho, might find it on google.
I bet you don't even use iTunes now I've written a mini-howto tho
I've found a few apps for tagging mp3's