Picture 1383
These are called Cantilever brakes.  They come on all sorts of bikes from BMX to road.  They allow for big tire clearance and are very simple, pure and robust in design.  The one problem for these brakes is that after awhile the spring tensions get uneven and one side would get pulled towards the wheel as pictured above. 
Picture 1388
Now the way the tension is regulated on these torsion springs are these little holes pointed out by the arrows.  The red arrow position is the highest tension position, the green is the lowest, and there’s the position in between.  You always want the highest tension possible in the springs, this provides better brake lever return and braking feel. 
Picture 1398 Picture 1391
As pointed out in the first picture, the right brake caliper is pulled too far in, making it rub the wheel.  This problem evolves from the imbalance of tension between the right and left calipers, in our case the left one having more tension than the right.   As Said before, you always want the most tension possible, but in this case both calipers’ springs are in their maxed out position so the next best thing to do is lower the tension on the left caliper.  First remove the wheel and then take the cable off of the calipers to release them.
Picture 1389
Use an Allen wrench to release the caliper. You don't have to undo the bolt all the way, just enough so that the spring is free.
Picture 1392 
Now you’re free to mount the spring’s end on the middle hole (for less tension.) 
Picture 1395 Picture 1393
Cock the caliper all the way back as pictured.  Before you screw the Allen bolt back down you want to make sure that the upper end of the spring catches and sits in the slot underneath the caliper.  If you miss this the caliper wont seat right and there wont be tension on the spring once its in its working position.
Picture 1396
Now screw it down slowly, checking that the spring sits correctly as mentioned.  After that, reconnect the cables, install the wheel and see how the calipers sit with respect to the wheel.  There should be equal distance between the wheel and both brake pads.