Liz, I'll second Brian's recommendation for Vines to Wines, which is especially valuable as a concise guide to both growing grapes and making wine. One of the electronic formats that Brian mentioned may be Lum Eisenman's "The Home Winemaker's Manual", which is avaiable online at
http://www.geocities.com/lumeisenman/ and is very thorough. Everything you'd want to know is there.
Beyond that, although basic winemaking isn't hugely complicated, it's too much to share with you in a forum like this, I think. Do some reading and then come back and ask specific questions. The good new is that IMO, making red is simpler than making white for the reason that quality whites are generally fermented at lower temperatures (in the 50's) that require refrigeration to reach while reds run in the 70's and 80's (F, of course) and so are happy at room temperature plus the self-heating you get from the fermentation.
Whether your must needs sugar depends on how ripe your fruit is. How to measure that and whether to add sugar ("chaptalize") is one of the things your reading will help you decide. Beyond reading, one more suggestion: visit your local homewinemaking store (Yellow Pages under beer or wine making), ask for advice and buy a beginner's kit, probably available for well less than $50-$100, depending on what's included. Or just go watch granpa - sounds like he's experienced