It could be that everyone knows how to do this. But just in case...
You have to find the "Name Your Own Price" section.
Then you fill out your info. Dates and city. One room or two. On the next screen you get to pick how many stars you want. I usually pick two, two and a half... and they often upgrade you to a 3 1/2. It's a nice sign when that happens.
I wasn't that fortunate today. I know all the motels will be full that night though due to the reason we'll be needing one (big craft show). But hey... I like a hot shower. We were considering camping out at the sight.
They will also need your credit card number for this step. You have to read a few lines, choose if you want trip insurance, then initial that you read it and... bang. Bid. If you get it you will get this next screen.
So keep in mind... you do not get to pick your actual motel. Price line surprises you with one. If it's a week day and not a peak time... I'd start out with a $45 bid on a 2 1/2 star.
If they do not accept your bid... you have to up your price and I think lower your star rating? Then you can bid one more time.
Otherwise you have to wait a day. It really comes down to how desperate you are and all.
When we went to visit Carla, we bid on a room that morning and slept in it that night. Fun!