Updating Foreign Key

Hello Everyone,
I have two tables UserInformation & ContactInformation. UserInformation contains database of Users. Every User has its own set of Contacts Saved in ContactInformation. In UserInformation ,ID(User's ID) is a primary key. In ContactInformation , UserID is a foreign key which has been related to ID of UserInformation .
Now, when i insert into the table ContactInformation , i want that the foriegn key UserID should also be saved so that it shows that the contact is of that particular User. How do i do that?
Thanks,
Chaitanya Pandey
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