How to make the rest of the mask transparent in Premier Pro CS6? I'm trying to highlight a part of my video. Since I'm totally new to video editing on Premier Pro - I'm not sure if this is the best way of doing that, but I'm using masks.

I have a title sitting in video 2 row, in it a have a rectangular mask (100% opacity)



I then apply a Track Matte Key effect on the video I'm trying to highlight, and get the following result:



This seems like a step in the right direction, but I can't find the place to change the settings of the mask to enable transparency. The intended result is to have dimmed out frame, with only the masked area fully shown.

This is the Effect Controls screen for my video:
Ok, now that I was able to reproduce your technique thus far, I can fill in the missing pieces.  Your use of the Track Matte Key produces a layer that is transparent everywhere other than where the mask is present.  You need to layer it overtop of the video that you want behind it and you need to apply the dimming effect to the background layer.

In your example, Move video 2 to Video 3 and copy Video 1 to Video 2.  Leave the track matte key on Video 2 and remove it from Video 1.  This will layer the highlighted area (Video 2) over the full video (Video 1).  You can then either reduce the opacity or apply a brightness reduction to Video 1 to make it appear more subdued and get the look you are going for.