How do I find an Interior Light relay?

Ok, I've posted before about my interior light not shutting off. And how I've checked everything. door jamb switches, replaced dimmer/light switch, etc etc. Now I have been told my many that it's probably the Interior Light Relay. Where do I look for that and how do I go about testing/replacing/whatever I need to do to fix it. lol Any help would be greatly appreciated. Now please take into consideration that I'm pretty much automotive illeteriate so speak in car baby terms for me. lol ty everyone!

go to an autoparts store and look at one of there manuals. it will show you exactly where it's at. or just ask the guy behind the counter