Most of the details which you used to register can be managed by going to My Account > Manage Details. Here you will see all of your personal information and most sections have an 'Edit' button which can be used to change them. When you change your details it can take a little while to take effect, but should normally be processed within 24 hours.
The only exception to this rule is your name which unfortunately can't be managed via the My Account section for security reasons. If you have had a name change recently and wish to update the name on your account, simply send a copy of your marriage certificate or deed poll certificate to firstname.lastname@example.org, or alternatively, contact our 24/7 Customer Support Team via the Live Chat icon in the bottom right hand corner of your screen.