I'm totally lost

[WhoisAnthonyG]

So I downloaded an undertaker attire I wanted, I recieved a zip file containing a txt file and two .pac files. I added those to the pac folder and reloaded the game. When I go to select the Undertaker however the game crashes and as a result I needed to reinstall the game which takes forever. I also tried following Pozzum's Cheat engine tutorial and I can't make any sense of that either. I am very new to modding and I am mainly looking to update attires and possibly ad some better than CAW models to my game. Is there a definitive tutorial or way to do this? Do I need software like xpacker and cheat engine? I have searched this forum and come up just as confused   Sorry if this is a redundant cry for help!