Juice is all that you need to make wonderful wines!
Starting with juice simplifies everything because one carboy serves as both your Primary fermentor AND as your Secondary fermentor, too!
It doesn't matter if it is fresh squeezed, bottled, or frozen concentrate, or a mix of any or all.
Just make sure that it does NOT have any chemical preservatives added, other than Ascorbic Acid (Vitamin C)!
Use a hydrometer to determine the potential alcohol of the juice. Most processed juices are around 1.050, which will yield a wine of 4-5%.
By heating, NOT boiling, some of the juice, and adding about two pounds of sugar to a five gallon batch you can raise the ABV to around 8-10%.
Just fill a carboy to within an couple of inches of the neck, to allow for any krausen that your particular choice of yeast may generate (some are worse than others), with your favorite juice, or juice/sugar mix, pitch the yeast, install an airlocked stopper, and wait one month to allow complete fermentation.
Let it age for at least another month, and it is ready to bottle.
Cheers!
oxeye