I would suggest to learn C++ before using DarkGDK.
If you don't want to pay any money for it, head to
http://www.cplusplus.com/, they have excellent resources and tutorials.
If you have about $20 on hand, get this book:
http://www.amazon.com/Beginning-C-Through-Game-Programming/dp/1598633600/ref=sr_1_2?ie=UTF8&s=books&qid=1258429460&sr=8-2
You will not be disappointed from it. The only tricky parts of the book is when they first explain references, pointers, class inheritance, and polymorphism. But once you've completed book, just reread it (without doing the activities), it will make 100% more sense to you.
http://www.darkgdk.us/ <- New community for DarkGDK coming soon!