They’re offered at The Art Center in Highland Park, which is where I go (although I mostly do acrylics), but that’s pretty much opposite side of the world if you’re in Tinley Park. There’s a similar art center in Evanston which also ain’t much help, and the School of the Art Institute presumably offers such classes downtown.
I suspect that if you call one of these places, they’ll know of other such places nearer to you?
BTW, sometimes there’s not enough students in the Beginner Oil Painting class, but there will be some sort of instructed studio class for painters, beginning level. If you can talk to the instructor in advance, they can usually accomodate, to teach you basics.