How would I get into modding

I'm not sure if this is the right place for it but I thought this was the closest. I've never actually modded any game before so I am completely new. I was thinking of buying WWE 2K17 for PC but I decided without Mods there wasn't a point. I would only like to learn a few things to begin and I may ask for more later.

What I would like to know-
*I would like to know how I would go about porting characters from previous games (2K15/16). Would I need to buy those games as well or no?
*I would like to know how to mod the cutscenes from MyCareer and Showcase (the ones the game doesn't give you in video editor). I just wanna pretty much know how to change the arenas and characters in the cutscenes. l'd assume I would need 2K15/16 if I wanted to Mod there cutscenes.

What would I need?-
*What program would be the best to start modding (the simplest is ideal.)
*Would I need the games to be able to port?
*This doesn't have anything to do with modding but what is the best program to capture my gameplay?