Hi..
This is only simple example with 2 textboxes,

Textbox1 is owned by mainform.frm
Textbox2 is owned by second.frm

You fill some values to textbox2 and bring the text to main form.

You should do this:

in second.frm
mainform.textbox1.text = textbox2.text

Good luck

Regards
Winanjaya