Depends on what type of "textbox" - I hate that phrase. Sigh.
If it is a FormFields textbox, then text in the box is the .Result property of the FormField, as in:
ActiveDocument.FormFields("formfieldName").Result
Is it an ActiveX textbox? If so, then text in the box is the .Text property of the Range, as in:
ActiveDocument.InlineShapes("Textbox1").Range.Text
What do you mean by "populate"?
Gerry