If you are logged in as the master administrator, in the upper right corner of your page is a green button called 'Go To Admin'. Click on that. This takes to the screen below:

Click on the Preferences tab, and then in the middle column there is an option for 'Auto Registration'. If checkmarked, this means that when bidders register they are immediately emailed their new bidder/user# and password.

If auto registration is not checked, this means that you as the admin will need to manually approve the bidder. To do this, click on their User# from the Users page, and in the bidder profile enable bidding privileges.