Sounds like you will need to determine the last row. Try this

Sub WriteLastRow(
Dim LastRow As Intege
With Worksheets("Sheet1"
LastRow = .Cells.Find("*", [A1], , , xlByRows, xlPrevious).Ro
.Cells(LastRow + 1, 1) = Me.Textbox1.Tex
End Wit
End Su

Kevin