The first time you place a bid, you'll see the option to create an account by adding a password on the checkout page. After that, the system will remember you so you won't need to sign in again.
Alternatively, you can click 'log in' in the header at the top of the page, where you'll be prompted to either log in or create an account.
The reason why we ask people to log in is that we can streamline the bidding process -- from outbid notifications to receipts to being connected with your item at the end.
