Pls help me on this. VB6

These are the type of steps you need - we do not write your code for you

1) create a form
2) on the form place a text box - I'll assume it's name is textbox1
3) create a label next to the text box with 'input' as the text
4) on the form create a list box - I'll assume it's name is listbox1
5) create a label next to the list box with 'data' as the text
6) add some code the the textbox1's 'On Enter' event to add the data to the list box - it will be 'something like' listbox1.Items.Add(textbox1.Text)

6) edited .. you should have something like this

Private Sub textbox1_KeyPress (KeyAscii As Integer)
    If KeyAscii = 13 Then  ' The ENTER key.
        listbox1.Items.Add(textbox1.Text)
    End If
End Sub

but obviously you'll need to consult your VB6 textbook or reference for the specifics