You have to select the target, then lock onto it with the radar. It's the "Home" and "End" keys (I think). You'll see things happening on the radar screen as you do this. Once you see how it works, it's easy. Doesn't always work, though. There are "parameters" in the software that mimic the real life limitations of the missile. G's can't be too high, angle can't be too large. That type of thing.