I began by reading "The Heart Rate Monitor Book for Cyclists" by Sally Reed.
She has a lot of practical info and workout suggestions for road and stationary bike training with a monitor.
The formulaic approach to calculating max heart rate didn't work for me... I'm 45 years old, and worked up to 196 bpm after an hour of intervals on a stationary bike, using a polar heart monitor.
Using that max, I've trained all season and ride comfortably over 100 miles at 145 bpm, or roughly 75%.
Breaking into the 160's on hillclimbs doesn't concern me too much. If I remain in that zone, 80% and up, for too long, the lactic acid builds up, my legs ache, and recovery takes days longer.
This is my first year training with a monitor, and now I'm addicted to it. It paces me more effectively than any other tool, and helps me avoid adductor muscle cramps which routinely plagued me in past seasons.
Sally's book is good reading, though it is a bit chart-heavy by the end. I still found it to be a big help.
Good riding to you!
Steve