how do I contact the sellers?

In the "Contact Dealer" box you can message them directly and indicate your interest in the vehicle. You'll have a chance to customize it a bit more at the bottom where it says "add comments." You can also click on the phone icon to the top right of the same box, enter your phone number, and then it'll dial them. Lastly, you can also Google their name and address and then call them. I'm not sure how the process works for private sellers, though.

Where do you find tthe contact dealer box?