I'd wait a bit until you've figured out how the stock sim functions first. That said, MAW comes with very clear "this is what you do" instructions, so try reading them and applying them. First though - is your copy of CFS3 up to date with the patches from MS? Mission Builder et al? It needs to be, or MAW, ETO, etc, won't install correctly. It also needs to be pure vanilla - no add-ons in your base install. MAW and ETO copy your original install to another location on your HD and then install the new files into that new location. Your original install is unmodified.