We will send your account activation to your email and this email will be used when you're login to the website.
Display name is name that everyone see for your account. Only alphanumeric without spacers are allowed, some reserved words are not allowed to be included in the name such as: admin, moderator, staff.
Your role will determine the experience when you're using this site. For easier use, menus, pages and notifications will be customized based on your role. If you're unsure, just select 'Both', you can change it later in your profile's account.