I take it you mean a route rather than 'making a map'?
You can insert points in a route using the insert tool. Basecamp (assuming it's not set to direct routing and that the map you're using is routeable) will then reclaculate the route to include the new points.
If the program puts me on I 80 and I want to use I 70 how do I change the route. When I insert a way point on I 70 the program will take me off I 80 to the way point then back to I 80 How do I just program it to use I 70?
The forum you're currently posting to is for creating your own maps for handheld devices from scanned or downloaded imagery and has nothing to do with route planning or Basecamp.
Sadly, there is no way to simply tell BaseCamp, Mapsource or your Garmin GPS device to follow or use a particular road by name or route number.
You can, however, try either or both of the following:
a. Add enough via points to bend the route to your will. That usually means more than one, or
b. Drag and drop the route over to the road you want to use. Again, you may have to do this on several sections until it conforms to the path you wish to take.
BaseCamp has some videos on line which might help you with your question.
Since it sounds like you're new to this, you must be very careful when setting a waypoint or dragging a route to a divided highway (like an Interstate, or any freeway) to place the point on the side of the road going in the proper direction. Much confusion results when the GPS (or Mapsource) tries to route you back and forth via the nearest exits to hit a point in the lane going in the opposite direction. This usually involves a careful review of the waypoints under high magnification. Maybe there's an easier way to deal with this, but I've not learned it.
