DIY ebikes takes a little reading first but at the end it's rewarding plus you save a ton of money over a fully built ebike from a store.
Here are the links to start with:
After you selected the type you can have a look at the different models here : http://electricbike.com/forum/forum/knowledge-base/motors-and-kits
For a first build I would stay with a BBS02/BBSHD mid drive or a complete hub motor (hint we are a big fan of mid-drives like the BBSHD and BBS02)
A BBS motor is pretty easy to install you just have to know if your bike can take it (the vast majority can):
Also the installation procedure : http://electricbike.com/forum/forum/knowledge-base/motors-and-kits/bbshd/7369-bbshd-installation
For batteries, there a voltage and Ah (ampere-hour = range) any BBSxx motor and hub motor can take 48-52V, the ah is the range, the rule of thumb is about 0.4ah per mile, so a 14ah battery would get you about 30 miles at 15-20mph, on a normal bike, on flat roads, very little head wind, and little pedal effort. You can get more or less depends on how you ride your bike.
When ready you can find the complete kits here : http://lunacycle.com/motors-and-kits/
All the rest of the resources at your disposal : http://www.electricbike.com/forum/forum/knowledge-base/general-aa/7617-electric-bike-web-resources