For alphabetic key you can use
<code>
Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
If e.KeyChar = "a" Then
MsgBox("got it")
End If
End Sub
</code>
But for enter key you can try
<code>
Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
Dim data As String = TextBox1.Text
If e.KeyChar = Chr(13) Then
TextBox1.Text = "http://www." & Data & ".com"
End If
End Sub
</code>
try using different combination for different results !!