You can take old tape recordings and feed them from your headphone jack out to the 'line in' input of your computer. You need to adjust volume for maximum effective range of your computer recording software. Some years ago I bought CoolEdit Lite and it's a wonderful intuitive program. I have done little actual recording direct to computer, my main concern with that would be to maintain consistency in mouth-to-mike difference and other typical recording concerns.

As for inputting it into wave format, if you are simply recording monologue, I guess Mono, for speech you needn't sample at higher than 20,500 KHz. This will give you a .WAV (WAVE format) program which uses about 2.5 megabytes of memory for every minute. You can convert it to mp3 format using Apple iTUNEs amongst other programs, and using the custom selection and selecting 128 kByte/ sec stereo rate with VBR and MONO checked will result in a 64 kByte rate which will use about 0.5 megabytes of memory for every minute still sounding very good. In fact, you can probably select 64 kByte/ sec stereo rate with VBR and MONO checked which will give you 32 kByte rate which will use about 0.25 megabytes of memory for every minute and still sound good.