Do you mean books on old audio tape?
Neither overdrive nor digital editions is the right software for this.
You need to record the tape onto an mp3 or similar file (maybe aac for iPod?);
there are lots of free programs around for that; Audacity is one but may be more complex than you need, I can't think of a specially good one right now.
Then copy the file onto the iPod however you usually do that.