You must be a registered and logged in user to place a bid for an item on the site.

Once logged in, just visit the page of the item you are interested in and enter the maximum amount that you are willing to pay for the item in the box containing the number which represents the dollar amount in USD currency and then select the "Bid" button.

The site uses proxy bidding, which means:

You decide how much you're willing to pay, so enter your confidential maximum bid.

Your proxy (the system) engages in a bidding war with other proxy bidders, as well as live ones, while you go about your business.

At the end of the auction, you check back in to see how your proxy did. If other bidders outbid your predetermined maximum, you don't get your item. But otherwise, you're the winner and the final price might even be less than the maximum you had been willing to spend.