Stair bashing (Its not called bashing for nothing!) is not very hard to learn, and success is largely dependent on your confidence. Whether you go forwards or backwards, your success largely depends on a few things.
First off, you must have the basics of skating down to a fairly proficient level. If you can't do a 180, you really shouldn't be trying stairs because that is a skill that is above your level. But if you have a general skating ability, don't fall over while skating down the sidewalk, and have reasonable balance, read on...!
The key to riding stairs forwards is speed. Every beginner I have taught has gone too slow, and had to run out of the stairs. You need to go a moderate speed, about a slow jogging pace, when you try and ride stairs.
The next factor has to be foot position. Though you can divide your weight between feet any way you want while riding steps, the easiest way to learn is with the weight spread fairly evenly between your feet. Your feet should be directly under you, with the toe of your back foot near the heel of the front foot. The width is not very important, as long as you have balance. Just try and keep them around 6 inches or so apart. When most people hit the stairs, they tend to tighten up, and they let their feet drift together. This is usually bad, as they soon lose their balance and fall. You MUST keep your feet staggered, at least while you are learning, or you will fall. Have a friend look at you and tell you what you are doing with your feet, or just pay close attention yourself. Also be sure to keep your knees bent, much like a shock absorber, otherwise you will go flying and/or end up with hurt knees!
Just like you wouldn't run a marathon your first time jogging, you shouldn't try to bash down that massive 100 stair flight your first time out. Start out riding down the smallest flights that you can see. Riding off of a curb is a descent start, and will help you learn the form, but I wouldn't be afraid of going down three or four steps to start out with. Then you can work up to the long, big sets. Its hard to explain, but once your body understands what it needs to do, the size of the flight doesn't really matter. If you can do that flight of 6 steps easy, a flight of 20 shouldn't bother you.
Oh.. A final note.. Make sure the steps you are trying to do aren't too steep! Though dimensions are kind of arbitrary, a good flight would be steps of about a foot long and 6-9 inches high. Once you start getting the ones that are that are perfectly square, you begin to get into the stairs that are less fun, and more like 'WATCH OUT I'M ABOUT TO LOSE IT BIG TIME!!!'. Most stairs are OK, so don't get all paranoid if you see a flight that might be steep :) Also, your back brake will get in the way, but the stairs are still possible. However, taking it off is much better!
So.. Keep a descent speed, with feet staggered, weight even, firm stance, and try to glide over the top of the steps. You aren't going to walk down them on skates, you want to glide over the bumps.
