Hi Mumof5, welcome to the forum.
Congratulations on getting diagnosed and look forward to starting your treatment. All going well you should notice a big improvement in your energy levels and very likely an improved libido. When you're tired and fatigued all the time, the sex drive is often the first thing to go - hopefully it will also be the first to come back.
However I should probably warn you that CPAP isn't a miracle cure - some people experience an immediate amazing recovery, but for most of us it's a journey with two steps forward and one step back. Many people feel an initial rush of energy followed by a relapse, while others just get a steady improvement over time. I'm not saying this to put you off, just so that you have realistic expectations.
Getting the right mask is probably the hardest part - every face is different and there are dozens of different masks on the market. Getting the one that's right for you might take some trial and error. There's a pretty good write-up here:
http://www.apneaboard.com/wiki/index.php/Mask_PrimerYou may also find that the initial pressure settings aren't optimum and need to be adjusted. The best way to optimise your settings is to use the free software Oscar. It lets you see what's happening on a breath-by-breath basis all night. You can get Oscar and the instructions via the links in my signature.
Good luck with your treatment, and best wishes.