How do you locate and change the main relay on a 1992 Integra?

Main relay to what? There is no "main relay". You have multiple relays for a variety of functions. There is what may be considered a main relay, it is a "circuit opening relay". It controls the function of a variety of circuits (I.E. fuel pump, ECM, starter). Goto AutoZone.com and look up your vehicle and see if their website gives you the location for this relay.

Actually there is a Main relay it is under the steering coluum it is a 10mm bolt that holds the hazard flashers and the Main relay it is a burnt brown color easy to fix best way is to take the kick panel off (the 2 Phillip screws) and a couple clips and you will a little black box and behind it there is the Main relay =)