1. Obtain skates. You can either borrow them from someone close-ish enough for government work to your shoe size, rent them from an appropriate establishment (for some strange reason the local Methodist church is that establishment here), or if you’re really insane you can just buy them. Skates are not as cheap as you will remember them being when you were a kid.
2. Obtain protective gear. Do not skip this step. At the very least* you want kneepads and wristguards, being the most likely points beside your ass you’re going to fall on. Your ass is probably well padded already. (Except for one particular point, which you may- excitingly- discover.)
3. Locate a good place to attempt skating. The sidewalk is not a good place, as you will rapidly discover if you try it. Yes, that is probably where you learned to when you were eight. You aren’t eight anymore, you are much further off the ground, and the amount of mass you have to interact with gravity has increased greatly. Even if it looks fine to you, taking a broom and clearing the chosen space, if outdoors, of gravel will do you lots of favors. Skate wheels aren’t designed for offroading even a little bit.
4. Put on protective gear. Put on skates.
5. Stand up.
6. Attempt to move forward.
7. From your new position on the ground, assess yourself for injuries, and determine if they are serious enough to justify taking the damn skates straight back off again. Common options include groin pull and bruised tailbone.
8. Try to find either a friendly person to literally hold your hand, or a vertical surface that can be slightly leaned upon. Try to do this somewhere with walls. When you come back, if you can come back with a baby stroller or shopping cart, these tools will help enormously.
9. Practice skating in a straight line from wall to wall. Now is a good time to quietly explore and discover every single tiny stabilizer muscle you don’t use at all in any non-skating capacities.
10. Because you will be doing it whether you call it practice or not, practice falling. You want to fall onto the bits of yourself that are actually well protected, which in most cases if you bought remotely adequate kneepads will be your knees. Although you may be wearing wristguards, never rely on them; wristguards suck and they will only help you a little. Even if you don’t break your wrists, falling onto your hands is a good way to break your thumb. You are not supposed to fall backwards, but this will happen anyway; attempt to fall on one side of your ass or the other. Falling on it straight back and center will bring you naught but woe. If falling at speed and knees are not an option, try to fall on your hip and roll. Again, it is likely to be already well padded. If you are female, falling on your chest is undignified but also a well padded area. Try to keep your limbs pointed in roughly the same direction and not to sprawl.
11. When you are walking, running, or carrying something, the best way to stabilize yourself when you feel you are losing your balance is to lean your weight back on your heels. When wearing skates, this will have wacky results. The correct answer in skates is always to bend your knees and lean slightly forward. This will either stabilize you or lead the fall the way it’s supposed to go.
12. Your toe stops are not for stopping, unless you are rolling very slowly indeed. Your toe stops are for ninja tricks you may learn later. Also, if your skates are rental or stock, they are probably also mostly decorative. If you want to stop without the aid of something vertical, you have to learn to make friction work for you while wearing a device mostly designed to reduce friction.
13. Do all of this for many hours. Learn to do it on one leg, which is a surprisingly useful base skill when learning ninja tricks.
It helps to have a small, perpetually perky woman shouting at you the whole way, mostly in the sense that if you do learn, you will eventually be allowed to hit her as hard as you can. Good luck.
*At the very least for just absolutely green starting out. If you keep doing it long enough to be capable of any real speed at all, you NEED a helmet and you SHOULD also get elbow pads.