Public Class Form1
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        With RichTextBox1
            .SelectionColor = Color.Blue
            .AppendText("ABCDEF")
            .SelectionColor = Color.Red
            .AppendText("GHIJ")
            .SelectionColor = Color.Green
            .AppendText("12345")
        End With
    End Sub
End Class