New to Model thingy

[crazeestudio]

right so recently i downloaded this file that changes a weapon to frostmourne, and i've been reading up on a few of tutorials as to how i can apply that file i downloaded in the game , from what i understand i need mywarcraftstudio , so i got it , but i still dont get how to use it , and im suppose to be able to change the weapon that i want to turn into frostmourne , the default was legacy to frostmourne , but since im not using a legacy on my characters i was thinking of changing The Unbreakable Will into Frostmourne , could anyone help me out with this ? I'd really appreciate it , thanks