1. Right click the shortcut icon of Toribash in your desktop
2. Choose Properties
3. Press Open File Location
4. There, go to data -> mod , and save the file there
5. Open Toribash, go to Free Play, type /lm modname.tbm (it's case sensitive, so if the mod would be SuPeRDuPeRHayPeRSoRdsoRs0MetHINg.tbm, you have to type it exactly like that, not superduperhaypersordsors0mething.tbm (also, remember to include the .tbm at the end.))
6. You should now be playing with the mod.