In this shot, the actuating arm is in the fully-on position - you need to remove the cable then wind in the pad adjuster (the screw behind the inner pad) until the wheel won't turn, then back it off enough to let it turn and reconnect the cable. That might be it, if it turns without rubbing and stops when you pull the lever then job done, but you may need to re-centre the caliper - slacken the mounting bolts*, apply the brake hard a couple of times then hold it on while you retighten the mounting bolts. If all goes well that's about it, but this process can involve multiple attempts to get everything right - slacken the bolts, twist the caliper, tighten the bolts ... you need to be able to see the gap between the rotor and the pads to tell where it's rubbing, or if one pad is further away than the other - a flashlight can help, or placing something white under the wheel to make the gap easier to see.

* the bolts that go through the caliper, not the ones that go through the fork.