This has been an unusually mild summer so it actually seems realistic to start fall vegetables this year. During the drought and 117 degrees of the recent past it was absurd to even consider trying. The soil temps would kill anything that wasn't a desert survivor.
With that said, be strong, be brave, pick up some seeds. Here are the guidelines from Oklahoma State University's Fact Sheet.
Did you know you can watch the videos of previous Oklahoma Gardening tv shows? Here's the best link to explore http://www.oklahomagardening.okstate.edu/ - the index is on the left side of the page.
Also - YouTube has dozens of good videos on seed germination, planting, etc. Try this link https://www.youtube.com/watch?v=V1NnFNs5TDs and then look on the right for more.