To store the entered value into the database, you will need to edit the Insert record Behavior (on the registration page) or the update record (on the profile page) sever behaviors.
You will need to have DataAssist installed to be able to make this modification.
With DataAssist installed, open the server behaviors window. window server behaviors.
In the list of server behaviors, double click on the Insert Record server behavior.
On the second page, select the new column, then click the lightning bolt next to value and select the form element.