Hi Todd,
Welcome to ALR. I'm going to buck the trend a little. Since you've never used a chisel, and probably not a rasp, or scraper, it wouldn't be a bad idea to get a piece of maple (if that's what your stock will be) to practice on and get a feel for the tools. Your practice piece doesn't have to be an actual gun stock. Is there a Woodcraft store near you? If not, they do mail order. You could get a couple of small pieces of maple for a few bucks.
If you don't have one already, get a book on building longrifles. My favorite is "Recreating the American Longrifle" by William Buchele, but there are others. Some of the steps will be different when building from a kit, but it's good info to know.
Then, as the other fellows have said, Jump in! If you get stuck, use the search function here on ALR, someone has probably encountered the same problem. If you don't find the answer, ask away. Have fun with your build.
-Ron