CEL once in a while

My check engine light comes on once in a while. Is there a way to pull what code it was even if it went away? Does anybody have a link on a "how to" kinda thing on pulling codes. Its a 93 rodeo btw.

I think the CEL is stored for like 30-40 restarts.

Autozone willl read codes for free, or you can buy a code reader for under 50 bucks.