Once you are logged in, you can bid on a lot several different ways.
To bid the amount already shown in the Minimum Bid Required, check the Bid box next to it.
To place a higher bid right now, enter the amount in place of the minimum shown and check the Bid box.
To place an "up to limit" bid, so that the auction will bid for you until you hit your limit, enter your secret limit and check the Up To box.
This auction has "soft" closing times. If a bid is submitted and confirmed during the last minute before closing, the time will be extended on that lot by one minute. This will continue until a full minute passes without a new bid on that lot.
Bid on as many lots as you like on one page, then click the Submit Bids button. Your bids are not fully submitted until you Confirm them on the next page.
If you see the current high bid shown in Red, you are the high bidder right now.
My Bids will show you the status of just your bids.