I would use one radio - button for true and one for false, because its boolean. There is a procedure
[press_radio_widget update_newsletter_p f "Yes"]
[press_radio_widget update_newsletter_p t "No"]
where update_newsletter_p is the variable name, t / f is the value.
If you want to use just one selectbox you could write on the -2.tcl page s.th like:
if { ![info exists $update_newsletter_p] } {set update_newsletter_p "f"}
the insert should be like values (...'$update_newsletter_p',..)
