I'm so glad we have a "young man" entering our midst.
First of all you need to look at a couple of web sites.....
http://winemaking.jackkeller.net/index.asp and
http://www.defalcos.com/recipeswine.htm and
http://www.brewmaxer.com/wines/index.html
There are a few others but in my humble opinion these a pretty good to great for where you are.
A quick answer to your question is 2 cans of concentrate for every gallon you want to make seems to be pretty standard. Check the above pages for sugar, pectic enzyme, etc. that you'll need to add.
A couple of comments....
1.07 might be just a bit low....think about upping your sugar content to oh, say 1.09 to 1.1 or so. Don't freak out.....there is no "right" answer.....play with it a bit. Make a BUNCH of one gallon batches and see what YOU like.
Racking to secondary at 1.02 is great and just what you should be doing.
This is a great hobby. It is one that will allow you to experiment and find your own style. So enjoy and remember, if you're not having fun then you're not doing it right.