Tried to tighten the brakes, won't grip at all I have a big problem. I know I could get this fixed with a mechanic, but really want to learn how to do it myself. I tried to fix (fool around) with my brakes a little the other day. The brakes are Shimano Nexave BR-IM70-R rollerbrakes. 

I loosened the "thing" that connects the cable to the actual brake pads, but when I tried to fasten it again the brakes don't grip at all. That is to say, when I pull the lever at the handle, the cable is pulled, but doesn't grip the brake at all. 

I have tried watching videos online, but none of them seems to deal with this problem. Also, I have tried to find the name of the brakes, but I am unsure where to look at the bicycle. Hope that someone would be able to guide me on the right path

Here are some pictures:
On the first picture, if you look closely at the cable right to the bolt at the center, you will see deformation marks from the previous clamping. The position where you have clamped the cable seems to be too slack. That is, too much cable is left between the lever and the pinch bolt.

To fix it, loose the cable, press the "thing" that rotates when you press the brake lever clockwise, and clamp the cable again at the new place.

You may end up taking up too much slack, permanently pressing the brake pads against the rotor or drum; in this case, find a compromise position between too slack and too tight. It can be done by using the adjustment barrel at the lever, if you have one there.