I work in a Winery. Yeast ferments things. you CAN NOT make wine without yeast. LUCKILY there is a little thing called NATURAL yeast! if u get things to the right temp then the natural yeast will kick in and ferment the goos for you. for a good wine u want a good sugar level - called bomeau (spelling? pronounced bow-may). the right acid levels are important too. for white wine you want to crush the grapes and get the juice AWAY from the skins ASAP. for red u want to ferment the wine WITH the skins. you also want a good size berry. a good sized berry is SMALL!
Table grapes are useless for winemaking - thats why they go on the table. conversely winegrapes are SHIT to eat.
2 products that will aid in the fermenting process are "diammoniumphsophate" and "Cerevit". just think of them as yeast food. they assist the yeast in the process.
When you are happy that the wine has reached a decent alcohol
content (or the yeasts have died) just bung the container in the fridge for a day or so. this should help seperate all teh crap to the bottom of the container. there are several fining agents u can use, our winery uses skim milk powder, which is mixed with water and then slowly added to the wine. NOT MUCH IS USED! i'm talking 20kg to a 130000 litre tank. then the wine is passed through a centrifuge which spins the solids out of the wine.
It is important to not let the fermenting juice go below 16 degrees celcius or teh yeast WILL die. it is also important to try and MINIMISE the contact the wine has with oxygen. the oxygen will discolour the wine and screw with the flavours.