Trying to set user IsAnonymous to false in profile

Hi
i trying to include a name property which is save in aspnet_Profile when registering user with aspnet_Membership
I try to assign a name to the newly registered user but at first it pop outa ProviderException saying "This property cannot be set for anonymous users."
Then i try to set the IsAnonymous to False in the code, but it say the property is ReadOnly
How do i fix this problem? Or is there any better way to do this?
Below is my code.
mb = Membership.CreateUser(UserName, Password, Email) Profile.Name = Name Roles.AddUserToRole(UserName, "Staff")
 
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