You have two bidding options to choose from:
Straight Bid - This is the most common. What ever the bid amount entered, that will be the high bid.
Auto Bid - Also known as Proxy Bidding, you can enter your max bid and our system will bid the next bid increment on your behalf until it reaches your max bid.
1) Click "Auctions" on the far left then "Manage Auctions."
2) Click on the Name of your auction.
3) Click "EDIT".
4) Scroll down until you find "Bid Options". Select the bidding type from the drop down.