You must have Admin Level - Webmaster or above access to see job sign-ups.
Click Events & Competition > Events from the left navigation menu.
To the right of the event, click the green Job Signup button.
Click Find Workers - This will show all active accounts.
Use the filters to find the necessary information:
Account Name
Day/Session
Date Range of Jobs/Slots -- relates to the past and future jobs information
Has Job -- Yes or No
Click Search.
Click on the Account to move directly into signing this account up for a specific job.
You can send a custom email to accounts by clicking the check box next to the Account Name column or by desired names and clicking the Email button.