For beginner canners this is the best to start with. It uses the water bath canning method explained here http://pickyourown.org/water_bath_canning_directions.php and very little time.
The type of grape that is used will determine the flavor. I used concord grapes that I found at a farmers market.
After gathering all the ingredients get your canning gear ready. Sterilize jars, get the water boiling.
Grape Juice: 6 quart Jars
6 cups grapes cleaned and picked from stems
6 Quarts boiling water- different from water bath
Pour the 1/4 cup sugar and 1 cup grapes in each quart mason jar then pour boiling water into each jar leaving 3/4" head space. Wipe the rims and place a new canning lid on top, screw on the ring. Process in boiling water for 15 minutes. Take out and let sit for 24 hours. After 24 hours check the lids to make sure they are sealed it shouldn't "pop" when pressed. If a "pop" does occur refrigerate and use with a 3-5 days.
Congrats! you just made grape juice. This is a concentrate- When ready to make the juice strain out the grapes and push out all the juice, then add about 4 cups of water and refrigerate. Play around a bit with adding the water- I once added too much water and it was only OK. Now it's not going to be as syrupy as the kind that is bought in the freezer section. Just grapes and some sugar.