You will have to have a range target to insert the address in. Assuming you have a bookmark "bmPerAddr" then something like this in the userform execute command button code:
Code:
Dim oRng As Word.Range
If txtPerAddr.Text <> vbNullString Then
Set oRng = ActiveDocument.Bookmarks("bmPerAddr").Range
oRng.Text = "Personal Address: " & vbCr & txtPerAddr.Text & vbCr
ActiveDocument.Bookmarks.Add "bmPerAddr", oRng