Reference a textfield from another webpage or web container

Hi, I’m completely new to Web development, and I’m wondering how do I reference a listbox or textfield from another webpage or container,
I tried webpage1.textfield.text but it doesn’t work,

do I have to make them public? or can I avoid that? I like to avoid public controls.

Also I fill all contact info into textfiels from a contact listbox on webpage2 , and on webpage1 I have a order entry listbox where one column has the contact info. so is it possible if I double click on the listbox on webpage1 it will open webpage2 “webpage2.show” and fill the contact info into the textfields on webpage2 base on the selection on webpage1 listbox?

Thanks.