Anyone have luck in inserting user email into database? everything I attempt is not working

Have tried all the hint codes out there and beaten them around to my own tune, with no luck

Inserting user email into database how and why?

Any code that you are working with already?

Can easily insert user email into database when registering new member like this:

let email = $w("#email").value;
let password = $w("#password").value;
let first = $w("#firstName").value;
let last = $w("#lastName").value;

wixUsers.register(email, password, {
contactInfo: {
"firstName": $w('#firstName').value,
"lastName": $w('#lastName').value,