Hello,
I currently created a page on my portal called "Administration Portal" the Administrators contacts can do a lot of things for exemple :
1- Create a new contact (edit / delete )
2- Add a new webrole (Administrator junior ...etc)
My question is : how can i assign a contact to a webrole from my page directly, i tried a lot of things it does not work
I know the relation between contact and Web role is :

I can't add this information on my List Form, doesn't exist on columns that i can add to my form list.
I tried something else : Created a new table where i add a look Up contact and a look up web role

A new record is succesfully added but it's doesn't exist when i try to see on the BackOffice on my Portal Management Contact => WebRoles.
Thanks in advance for your help !
(sorry for my bad english)
Samy