First, to clarify what I was talking about,
http://www.2carpros.com/forum/automotive_pictures/192750_ParkingBrake07SantaFeFig17_1.jpg
You take off the rotor/disc and find an opening on the disc that is not for the bolts (if there is one. There used to be one on the 99 to 2004 ish ford focus diesels in germany, but I’m not sure about yours). You will need to turn the disc until you see the adjuster, which looks like this:
This adjuster can be moved with a flat headed screwdriver as follows:
http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0996b43f/80/20/5a/58/medium/0996b43f80205a58.gif
As far as the tightness goes, what I do is I lift the car so I can get underneath yet still get to the parking brake (or just raise the rear on two stands), I pull the parking brake up two or three clicks (German cars 1 or 2, Japanese and US cars 2 to 3), then I check if the rear wheels can be turned with quite some effort by hand. If both are more or less the same, you’re done. If not, adjust them (after releasing the lever back to normal) to grip on firmly (you’ll feel that with your screwdriver, then loosen them up a bit, pull the lever to 2 to 3 clicks and try turning it again.
You really want to get to a point where you can barely move them on 2 to 3 clicks. And they should be evenly adjusted.
I also seem to remember (and just reconfirmed on youtube) that older Fords had an alternative adjustment screw somewhere on the back of the housing. Here’s the link for those (even though I’m pretty sure the Focus is way too new for that method)
http://www.youtube.com/watch?v=2IxW-cgOooM