Cannondale's "si"
divve said:
Were the BB and crankset included with your purchase? Otherwise, you'll have to source those separately. They're part of the propriety design of your frame. New that will cost your around $500.
To the original poster: if you don't understand what Divve is saying, look here:
http://www.cannondale.com/bikes/02/ce/model-2RR4K.html
The term "si" means that it uses Cannondale's proprietary bottom bracket and crankset design, which was designed, manufactured and used by Cannondale, and by Cannondale only. So he is correct that if your frame does not come with its BB and crankset, you'll have to buy these from Cannondale, or find a used one somewhere.
In general, if you have never built a bike from scratch before, I recommend against doing it without supervision from somebody with experience. There are many small things that you learn only from experience: proper cable length, figuring out if your cables will end up rubbing against your frames/parts and leaving scratches, etc.
It's not impossible, but you may end up with small issues down the line. And of course, there's the risk of finding out later that the components are not compatible.
As far as I can tell, aside from the BB/crankset issue mentioned above, the rest should be fairly straightforward, assuming that you can install the appropriate headset. According to the website, it's a Campagnolo Hiddenset, which is fairly standard.
Another thing is that you may need specialized tools to install these parts. I have no idea what tools are needed to install a Cannondale "si" BB/crankset.
At any rate, once the headset/fork/stem and BB/crankset are properly installed, the rest is easier to do, but at this point you already have 50% of your bike built up anyway.