If you look in the bottom left there's 3 buttons near the translation indications. The top one is the staging controls, which is default. Middle one is the docking controls, which changes WSADQE into RCS thrust controls, along with spacebar and CTRL (or shift, something like that). It also displays more translation indicators to help.
I was using that, but it is still incredibly difficult to get it exactly right, since I was attempting to dock with... well, a ship with a rather large nuclear engine and fuel tank, so that I can remove the thrusters from my station and send them back to Kerbin. Therefore, navigation with it tends to be a bit tedious, since angling is a must. And in this case, angling is a pain.
Well, you need ASAS and RCS, and to use the docking mode. Also the "fine controls" mode, since that helps RCS as well. First kill your relative speed. Then right click the docking port you want to dock to, select "set as target". Right click the docking port on your ship you want to use to dock, select "control from here". Hit "V" until you get to "chase" camera mode, then orient so that you're looking along the docking direction. Eyeball the correct angle for docking and orient the ship to that. Switch to translation mode, and gently nudge RCS with quick taps until your velocity vector is somewhere in the vicinity of the target marker on the navball, and your speed is within 1 m/s. Coast slowly until you're close enough to correct your approach angle, do that, and then adjust your velocity again. If you can't see your dockport, just keep your eyes on the navball, because it represents your docking port in this setup. Ideally, you will want to put your target marker in the center of the navball reticule first, and then do the final docking approach, rather than approach from an angle, but as long as you're going slow enough a slightly angled approach should still work.