[Erel]

You can use a code similar to:

Sub App_Start
    Form1.Show
End Sub


Sub TextBox1_KeyPress (key)
    If Asc(key) = 13 Then 
        textbox1.IgnoreKey
        button1_click
    End If
End Sub

Sub Button1_Click
    Msgbox(textbox1.Text)
End Sub

TextBox1 should be a MultiLine textbox.