The MiG-25BM SEAD/Bombing instant action mission has a mini-tutorial on the bombing procedure in the description. If you are using the RB instead of the BM, you can open the mission in the Mission Editor (the file is located in the Missions\QuickStart subfolder of the main mod folder) and remove the SAM site in order focus on the bombing.
Also inside the main mod folder there is a Tracks_Tacview subfolder that has a track file of the mission, though due to the nature of track files, the bombing might not be as accurate as in the originally flown mission (especially depending on the DCS version), but the procedure is the same.
The crucial aspect to a planning and flying an RB or BM bombing mission is navigation - setting the waypoints and altitude in a way that you can reach the appropriate altitude (around 19-21 km is optimal), the appropriate speed (around mach 2.2-2.4 is optimal), and appropriate direction at the appropriate distance from the target waypoint (around 100-120 km is optimal), so that when the autopilot is activated it has enough time to stabilize before reaching the bomb release point (the exact range depends on speed and altitude, but for the optimal altitude and speed it's around 40 km from the target).
Hope this helps!
