Approach Hold

As was said before, you need to open up the NG manual on page 1, and read, read, and then read some more! That's the only way to really learn how to fly this bird. I would probably stick to learning about the systems of the aircraft and how to operate it properly before trying to use the FMC, as the FMC is a very complex instrument in itself.If I remember correctly, when the FMC says that you're not on a 90 degree intercept, that means that you are pointing more than 90 degrees away from your next waypoint. Your autopilot won't engage unless you are within 90 degrees of the waypoint.