Thank you for asking something I can answer. I have a '91 and it is similar. For this job you need a towel, a drill/screwdriver, and two wrenches.
1) lay the towel on the ground partially under the truck and lay down on it.
2) under the truck the running boards should connect to the truck via brackets
3) using your wrenches undo the bolt(s) holding the brackets to the frame
4) move to the other end of the board and repeat removal of bolts
5) get up and move to the wheel well, screwdriver in hand
6) unscrew the screws connected to the wheel well
7) move to the other end of the board and repeat removal of screws - caution, if you are not supporting the board it should fall at this point
8) repeat on the other board
If i was not clear enough or I said something wrong someone please correct me.