remeber first time I needed winrar, I was like ??? whats winrar, and basicly got laughed out by my friends
anyways its simple to use:
Install (obviously)
Download .rar file you want (icon should changed to 3 books in a leather strap by now)
Double click the .rar file
click the Extract button.
choose folder extration path ''C:\Program Files\Mount&Blade\Modules\Sword of Damocles - Invasion''
Extract
Double Click MnB shortcut
Choose Sword of Damocles - invasion
launch.
Hope this helps for anyone who gets confused by winrar.
http://www.rarlab.com/download.htm the top of file named WinRAR 3.80 should work for you, it sais it has a trial so I just assume it does
Edit/added: You have to extract the files in the rar file directly into the module system I gave the instructions on how, use em