I have never done this but I understand you need a Video Capture Card.
This can either be a card that fits inside your PC case, or an external "box" that plugs into your PC.
You then plug the VCR into this capture card or capture box.
Dazzle are one company that make these, like this
http://www.amazon.com/Dazzle-Multimedia-DM-700 0-Digital-Creator/dp/B00005UK8H
Note that Video copied to PC uses up a LOT of hard disk space so if you plan to start doing video editing you need something like a 250Gb hard disk.
I assume you are going to make DVDs out of these Videos, and if so you also need a DVD writer (you do not make it clear if you have one already)