As a supplier, when you enter in a reverse auction you have to be clear about the specifications of good(s) or "scope" of service(s) to be provided in case you win the auction. Most certainly, you already discussed details with the buyer before the auction, and if required, you also got detailed documentation via email. On the auction window you will see specs and terms summarized, but the complete conditions and documents are the one you already received from buyer prior the auction start.
Review always currency and Base Value of the auction.
The field to place the bids is shown below, under section "Place a bid", and will be firm after click on "Ok" button.
Eventually, if you do mistakes, you can withdraw your offer with the button "Withdraw". This is however not available for the last 5 minutes of the bid. Don't wait until the last five(5) seconds to place your best offer, remember that internet connections have a delay of 4-6 seconds (and more depending on your connection speed).
In order to place your bid, click on "Ok" button.
How much time is remaining, before the auction closes?
On the right frame you will see the auction countdown.