Welcome to the forum! And no "letting you join", everyone is welcome here!
As for the trainer, click on the store tab above and go through the checkout process. When you are done (it's free, no worries) there will be a download button. click on that, save the .zip file, print, build. Any help, just post up in the airplane section and we will help you out. Just built another one last night in about an hour and a half for another member on here.