Need help getting model to replace pistol's model.

I made a pretty crappy first time model on the “SWEP CONSTRUCTION KIT” and saved it as a “TXT File” in C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\garrysmod\data\swep_construction_kit. I want to get it to replace the pistol’s default model, but i can’t find any simple tutorials for it, nor have i found any threads that can help me. I’ve never actually done anything like this so i’m paranoid of messing up and damaging something. In case it helps for you to know, i do have Notepad++ and i don’t have a “models” folder in the garrysmod folder, i assume i have to make that myself(which i got no idea how to). I’m really interested in making remodels for the workshop and i decided it might be a good idea to ask here for some help. If i have further questions, i’ll add it in.