The lap steel guitar's strings are raised high off the fretboard, sometimes as much as a half inch. So unlike regular guitars, you don't sound the notes by pressing the strings to the fretboard. Instead, you use a steel bar. Grip it loosely with the index and middle fingers and thumb of the left hand (if you are right-handed), and slide it on the strings up and down the fretboard. Produce the sound by lightly pressing the bar against the strings, across the width of the fretboard, while plucking the strings with the right hand.
Since you only cover one fret at a time with the bar, the lap steel guitar is tuned differently than a regular guitar. Instead of the E-B-G-D-A-E (from high to low strings), a lap steel uses open chord tuning, such as D-B-G-D-G-D for an open G chord, so that you can play more than one string at a time and stay in key.
The beauty of the lap steel sound is the slide. Pluck the string and slide the bar up to the note you want to play, and create a bluesy glissando that is the signature sound of the instrument. Place the steel bar directly over the fret bar of the desired note, not in the middle of the fret as with a regular guitar, to get the note in tune. Since it can be difficult to place the bar precisely, rock the bar quickly but gently back and forth over the fret bar to create a vibrato or quaver that will help mask any dissonance of the note. If you are playing an electric, experiment with your pickup switches and amplifier settings to create different moods or color. Another useful characteristic of the lap steel is the ability to hold a note for a long time, known as sustain. Combine this with the vibrato technique for the best effect.