Okay, as a former reader of The Flash I'll set things straight.
Wally West was a forensic scientist in the employ of the Central City Police Department. His uncle Barry, who was also a forensic scientist, was the Flash of the mid-to-late 80's.
One day, Wally was visiting Barry at the lab. Wally had discovered his uncle's secret ID in some previous story arc. Anyway, Wally asked Barry to show him how he became the Flash, so Barry, being a kind uncle, set up the experiment that had resulted in his being the Flash. When Barry ran the experiment, lightning crashed out of a clear blue sky, striking the experiment stand and Wally. Thus was born Kid Flash(don't ask).
Barry took Wally on as his sidekick to teach him how to use his powers and they had many exciting adventures.
Ultimately, in one of the first crossover events ever, Barry was killed in action saving the universe.
Wally reverently took up the mantle of The Fastest Man Alive in honor of his uncle.
Wally, and all the other speedsters of the DC universe, take their power from an extra dimensional enery field they call the Speed Force.
Besides the ability to run at speeds surpassing the speed of light, Wally's connection to the Speed Force allows him to increase his molecular vibration, allowing him to pass, unhindered, through most solid objects, generate a suit composed of pure Speed Force energy, thus nearly frictionless. Because of his great speed, Wally can also appear to "walk on water" by moving so fast over the surface that the surface tension is never broken.
Wally also has other powers derived from speed, but I can't remember any more because it's been a couple of years since I read any copies of the Flash.
