Find first empty cell in column and enter value from textbox

I have a textbox in a UserForm that I'm using to add a text str to empty cells in a column. Using the following code:

Private Sub TextBox1_Change()
    Range("A2").Value = TextBox1.Value
End Sub

I'd like to have excel look for the next empty cell the column. I found, what looks like to me, an elegant solution:

Range("A1").End(xldown).Offset(1,0).Select

I'm having trouble combining the codes and this is where I need help.

Thanks