Comprendre l'utilisation d'une listbox excel vba

Private Sub UserForm_Initialize() 
Dim Derlig As Byte, Lig As Byte 
With Sheets(1) 
     Derlig = .Columns("A").Find("*", , , , , xlPrevious).Row 
     If Derlig > 2 Then 
          For Lig = 3 To Derlig 
               ListBox1.AddItem .Cells(Lig, "A") 
          Next 
     End If 
End With 
End Sub 

Private Sub CommandButton1_Click() 
Dim Ligvide As Byte 
ListBox1.AddItem TextBox1 
With Sheets(1) 
     Ligvide = .Columns("A").Find("", .Range("A2"), xlValues).Row 
     .Cells(Ligvide, "A") = TextBox1 
End With 
End Sub