Select the name of the list (by default, your job board candidates are added to the "Job Board Default Theme".) Your list will display showing all of the candidates who have signed up for your job board.
To view the candidates who have opted-in to receive your emails, you can sort this list by selecting "Only Contacts Opted In." in the second Show drop-down. This will sort your users for you.
To see more information on this candidate, go to Lists -> Manage Contacts.
To see what job categories that candidate has signed up to receive emails about, search for them by any of the search criteria listed (Company, First Name, Last Name, Email, Phone, or List Membership). Once you have found their name, click on their email address to open their contact profile. Click on the "Accounts" tab to view if they opted in to receive your emails, this area will have a list of the categories they signed up to receive emails about.