My question is this I just want to know what do I use to allow my 688 to record on my computer with all the tracks. I need to know step by step because I never done this before
The 688 is a bit complicated to describe succinctly, but...
Assuming you're familiar with the basic operation of the 688, and you've already recorded program material to all 8 tape tracks,...
You must assign each tape track to output on each individual Pgm Buss, 1-8 respectively. Once having successfully set up the 688 "scene" (patch) to do that, you'd need a 'puter soundcard/interface that allows 8 simultaneous inputs to be recorded,... such as our friend above suggested, the M-Audio Delta 1010. Of course an 8x RCA-to-1/4" patch cable or "snake" would be required.