concord grape vine

When is a good time to cut back a concord grape vine-how far back-point of cut, etc. I would like to get more juice out of the vine next year and I would believe that would take proper pruning. Thanks for the input fellow gardeners.

Here's a reference that tells you what to do
http://www.ehow.com/how_172725_prune-grape-vine.html

Thanks ecrane3. Looked at the site, printed it, but now its dark out and I'll have to wait for tomorow. Have a great day!

Tempting photo!