People are able to update their details after they register, for example to upload a photo, by clicking on the link at the bottom of their confirmation email.
If they no longer have their confirmation email the website admin can action this to be resent to the email address they registered with. This article explains how to do this.
First, navigate to your Dashboard at the top left hand of the screen and click into the Online Registrations tile.
Click onto the registration form name to view the list of people registered. Next, click on the persons' name to edit their record and select the Resend Registration Confirmation Email button.
Now, the person can click the link at the bottom of the email to modify their registration details.