Best way to learn is go to the training arena and use the computed bomb impact marker that shows up automatically. Note your airspeed, your dive angle, and where your target is on the HUD when the bomb impact marker crosses the target. Work to get a consistent bomb delivery using that profile.
Then you can start practicing a low level profile to use when searching for GVs at low altitude. Usually you spot a target, pop up, roll into the target when it is at the correct angle below you, line up and release. That all happens fairly rapidly if your keeping the target in icon range.