1998 Chevy S-10 ABS

There are many different reasons the light could be on. The most probable is a wheel sensor reading out of spec or a problem with the sensor. I believe local auto parts stores will read the abs codes for you as they read check engine codes. I may be mistaken, but you must get the code read.
Some scan tools for sale at auto stores will read abs codes, but I beleive they are pricey. And the only way to turn the light off after the problem is fixed is with a scan tool made for this purpose.