For music off a CD, just pop in the CD, and Itunes will ask you if you want to import the music. Say yes. Once imported, the music will be sync'ed onto your iPod, or you can do it manually by clicking 'File - Sync Medussa's iPod".
For audio files on your harddrive, use "File - Import".
Itunes automatically grabbed all my pics and sync'ed them onto my iPod without even checking that this was something I wanted to do so if that happens to you and you don't want them on your iPod, from within iTunes, you can go to 'Medussa's iPod", and from there customize what folders of music, videos, pics, etc are sync'ed onto your iPod.
Podcasts are regular audio and/or video broadcasts. You can setup itunes to download any you like for you regularly. You can either search for them by going to the Itunes store from within Itunes, or find them through search engines like:
A couple of new ones I found and like are:
TEDtalks - I just watched one from July (31st I think) where a touch sensitive computer of the future like the one in Minority Report was demonstrated. I want one!
Other than those, I get a lot of news, economic and language broadcasts.
You can just do a search on your interests and see what turns up.
I haven't tried ripping dvds onto mine.