If it's auto tensioner, You need to load the tensioner back up and lock it as you said... fit the belt, release the pin
Dead simple... mind your fingers!!! As you'll end up loading it up near a full rotation

You not found the Focus section yet, it's just down the main page about half way...?
I'd also suggest just one thread maybe in the projects thread as your separate threads every half hour are quite frankly getting boring and taking the piss!
Just a thought... nobody on here minds helping out, we just don't want the general section full of separate Focus threads