Indoor Trainer FAQ's

I just bought an indoor trainer. I enjoy riding outside more, but only in groups because i (as well as my family) dont want me to get hit by a negligant driver. I plan on doing 1 group and 2 indoor rides a week. How do i gage an indoor workout (length,duration, intensity). Usually when im outside i will do 40 miles with a "B" group. Any workouts or tips would be great. My max HR is about 200, so ne thing involving HR training would be good, because im a newbie concerning that..
THX