Hi, welcome to the forums!
Is suspect your Beech is equipped with the WXR840, so its as generic as it gets tech-wise
Hence some suggested reading:
Optimum use of the weather radar (Airbus, but very general):
SmartCockpit - Airline training guides, Aviation, Operations, Safety
Airborne WXR Interpretation (Honeywell)
SmartCockpit - Airline training guides, Aviation, Operations, Safety
Both of them should give you a good starting point if you are new to airborne weather radars. I can't speak for the 400xp specifically, but there is no reason why it should be different from the Boeings I am familiar with - on takeoff you are trying to look along the projected flight path without too much ground clutter, a tilt of 10-15 degrees up should work. Reduce the tilt for the climb, in cruise you should try and keep the clutter just visible and periodically look lower to be able to see rain-heavy convective clouds. Same thing really on descent, your instructors should give you an idea what to look for and how to look for it, the rest you should be able to figure out for yourself. Cheers!