Alright, so if you have been going through the buttons chronologically, you'll see that I said that I won't help in the FAQ, but I meant for a specific game, so I'm going to link some things that I've used personally that has helped me at least get a grasp of what I am doing.
FModel
This is like the main thing you'll want to use when it comes to modding Unreal Engine games, it's breads butter really, FModel allows you to explore game assets and file structures through the games .pak files, which can have models, textures, rigging, and just anything that you'd expect to find in game files! Super duper helpful for model replacements.
UE Viewer
This is the barer bones version of FModel and is a little older but still could be nice! I have found myself once on a blue moon struggling hard with FModel and just being like, "Fuck this shit!" and using this. If you like older ui designs, then this is good for you, but I still highly recommend FModel over UE unless you know what you are doing!
Blender
Blender is a 3d modeling program that can make models easily! I use this to edit pre-existing models so that I can make it rig properly in game, this is the bread of FModel, Blender does everything that... Blen...Dont? Wait that doesn't... nevermind.