Creating a user

    If you want to create a new user, you'd use ASP.NET identity APIs like it is used in core.

    Assigning the user to a user group

    As of Umbraco 7.7 permissions aren't administered for the specific user, but rather for the user group(s) that the user is a part of. So to add our new user to a user group, we first need to get a reference to the user via the GetUserGroupByAlias method, and then use the AddGroup method for adding the group to our user:

    // Get a reference to the default "Administrators" user group
    UserGroup adminUserGroup = (UserGroup) us.GetUserGroupByAlias("admin");
    
    // Add the user to the user group
    user.AddGroup(adminUserGroup);
    

    To make sure that these changed are saved to the database, we must also make sure to call the Save method. The GetUserGroupByAlias method takes the alias of a user group - eg. admin for the default Administrators user group.