Yes, the wiki is talking about the heel brake. The first thing I would advice is remove the heel brake(s).
Learn to brake without.
Reason being: It can get stuck behind things. If you plan to learn any other discipline like aggressive rollerblading, you really don't want to try dropping in a ramp with that heel break still on your skates. Learn to brake 'properly' from the start.
I made the error skating a long time still with these attached. The moment I removed them, I almost had an accident because I wasn't used to it. I panicked and I wanted to slow down but I forgot I removed it some hours before I went blading.
Brakes ordered by times that I actually use them:
One foot behind the other in a 'T' like position. Pros: Easy. Usable at every speed. High controlability. Safe! Cons: Your wheels won't last long if you brake frequently. Don't forget to switch them up from time to time that both sides wear down at the same rate.
You were talking about going sideways when attempting this stop. Bend your knees (always..in every circumstance). Put your hands in front of you. Imagine that you are holding a joy stick. If go sideways to the right, move the 'joystick' / your hands to the left and the other way around.
Also, if you are still having trouble, learn to skate on one foot as long as possible first.
2. Turn Stop
I struggled long to get this one right, it's practically putting one foot in the opposite direction of your other foot and making a u turn, which will slow you down pretty hard. Really hard to explain in words, this is the best video I could find: Turn Stop Pros: Doesn't wear your wheels down. Good for braking at slow speed. It's fun. It's also a nice way to turn at slow speed. Cons: Don't try this at high speed. Hard to learn.
3. Power Slide
This is actually a reverse T Stop. There are two ways, you can do a 180° (jump and land facing backwards) or turn smoothly into a power slide. Tips: Get really low. Practice first while you're not rolling. Just jump into the right position and get that foot really low that you are practically braking on the side of your skate. After a while you can try practicing this when going really slowly. Video: (just look up Power slide on youtube, I can't post more than two links because I have no rep.) Pros: Really good way to stop really fast. Fun. Looks bad-ass. Good at high speed. Cons: Don't try this at too low speed. Hard. Wears both your skates and your wheels down.
4. Cess Slide
This is a trick but also a good way to stop. It's similar to the powerslide but it has a ton of variations. (a lot of grinds in aggressive rollerblading could be, in theory, a cess slide) It's actually grinding, but on the ground or surface which is not a rail or a ledge. Example: Cess Slide Pros: Impressive. A lot of fun on slippery surfaces (or when it's wet!). High speed. Good way to stop quickly. Cons: Don't try this at too low speed. Hard. Wears both your skates and your wheels down.
5. Plough Stop
Opening your legs, going really wide, and then when going back to normal position, push your force outwards but let your feet go like this /. It will make you slow down quite a bit. The wider you go, the more you'll slow down. Also when going downhill for example, holding your legs really wide will make you go slower. That' just plain aerodynamics.
Sources: I do Aggressive Rollerblading for two years now.