Combining audio files

[moose48fox]

I have a few audiobooks and I use Itunes to listen and manage my mp3's. The audiobook show as ~50 different songs and I would like to combine them into 2-3 spaces. I see Itunes has this option but I cannot figure out how it works. Does anyone know how this works or software that will do this for me then I can put it back on Itunes after?

Thanks in advance

Randy