If you don't see a bid button or a button that says "Sign in to Bid", that means that your auction is not open yet. Once your auction opens, you will see the button to place a bid.
If you expected your auction to be open by now, please double check the settings of your Auction Event by signing in to your admin account and going to Auction/Manage Auction Events. You can change the Start Time to open bidding right away. Be sure to Save the auction event settings when you are done editing the time.
Another thing to check on is the time zone. If you have set your Start Time for the wrong time zone, that would explain why your auction hasn't opened yet.