1931: The first electric steel guitar (actually the first electric guitar of any kind) was introduced by Adolf Rickenbacker. It was nicknamed the frying pan for obvious reasons and quickly caught on with Hawaiian guitarists. It's easy to see that this was a vital step on the way to modern pedal steel guitars. 
The Pedal Steel Guitar - a layman's guide
The pedal steel is a recent invention - a steel that we'd recognize as the same beast played today was not seen until the sixties. It was developed to solve a basic steel guitar problem - that slanted bar positions were required for anything other than standard chords on a non pedal guitar. If you used a major tuning you'd have to slant the bar to get your minors (or use two note formations). Extra strings, extra necks tuned differently - all these were tried and resulted in some wonderful instruments and playing styles that persist to this day. But the first time we really got to hear the pedal steel was through the medium of Bud Isaacs. In November, 1953 he played on a session for Webb Pierce. The song was the beautiful Slowly and Bud used the string bending from his single pedal not simply as a way to avoid a slanted bar, but as an integral part of the melody. Jaws dropped and lightbulbs went off. Steel players headed out to their sheds and began dismantling sewing machines, tinkering with their steels so they could get with the programme.
The mechanism of the steel, while it's reasonably complicated mechanically, performs a simple function. Whether it's a foot on a pedal or a knee on a lever the result is a precise increase or decrease in tension on a string or strings causing a note of higher or lower pitch than the string would make in its natural state. Strings are usually grouped in pairs so octaves will raise or lower together. So what? Taking the simplest example and one that most steel players first played (and loved it so much they wouldn't shut up) - the bar is placed, by the left hand, on the third fret, the ring and little finger of the left hand rest lightly on the strings behind the bar, strings 3, 5 and 6 are plucked and a lovely G major chord rings out; the left foot depresses pedals A and B as far as they'l go and the G chord magically morphs into a pitch perfect C major. At this stage most people are hooked. But there's more, much more. The left ankle rolls the foot off the B pedal while still depressing the A pedal and the left knee presses against the lever to its left and the C major becomes an E major. These are two of the simplest examples of the power of the magic machine. The novice is now consigned to a lifetime of tinkering, head scratching, wrestling with damping techniques, experimenting with tunings and setups, backbreaking car loads and excess baggage costs. But it's all worth it.
As this is supposed to be a layman's guide we'll start from the very beginning with a few things you'll almost certainly need, apart from the obvious ie a pedal steel guitar and an amp. We'll discuss these later.
This is the bar of steel that gives the guitar one third of its name. They come in all sizes and materials but mostly you'll use one a bit like this. It's solid unlike a bottle neck and is meant to be of a reasonable mass to get a meaty tone with plenty of bass response. A thinner, lighter bar will sound recognisably thinner and more trebly (a good thing in certain cases). It's really a matter of preference but I'd suggest you invest (and they don't come cheap) in the heaviest bar you can easily hold and manipulate. Get a small one for those times when you need a bit more bite. You'll find plenty of manufacturers. I use one made by Jim Dunlop. Unless you lose it in a bar room fight you're unlikely to damage your bar for a long while.
You'll also need a plastic thumb pick. Some players use metal picks on the thumb but I find them far too scratchy on the wound lower strings of the guitar and I'm sure they would decrease string life considerably.
Here is a finger pick to complete the picture. Some players use one, some three, but most settle for two. Again this is a matter of preference and will depend on your particular playing style. I used to try to use three but I found it hampered my chosen method of blocking the strings - with my picks and fingers. If you just let each note you pick flow into the next you'll get clashes, and, though this is sometimes required, you'll more often than not want notes to have a little space of their own. Some players use the palm of their picking hand to do this, some use pick blocking ie when a string has been struck the pick that struck it (or a nearby bare finger) comes to rest briefly on the vibrating string and keeps it quiet for the next note to come along. Some use a combination of both of these. There is also a method moving the bar backwards off the string that needs to be damped, or even damping it with the thumb of the bar hand. Suffice to say that blocking is one of the most difficult things to master on the pedal steel.
A volume pedal - this sits under your right foot and is something that's used for expression. You can certainly play pedal steel without one but you'll be missing that crying sound so often associated with it. It is simply a volume pot (potentiometer) operated by a pedal. The pot can become scratchy, normally only when you walk into an important recording session. These days many players are switching to light operated pedals that don't have this problem. Hilton is probably the most well known manufacturer. For a pot pedal Goodrich is the name you'll see most often.