Gr@sshopper! Many thanks!
Is this also a good starting point?
http://www.crw.org/CheapLights.htm
A more specific question: How do I begin to think about stringing a bunch of LEDs together? I think I could just about attach one bright white light to a battery. But how do I evaluate a string of lights? For example, it might be nice to have three or four red LEDs in the back and two amber LEDs in the front. They ought to be on one battery. How is it to be evaluated?
I had a glance at some book like Electronics for Dummies but it was too complicated. I do have to face the fact that there will be a learning curve here.