How to Highlight Text

Hi, I am currently making a Syntax Highlighter.

How can I highlight certain text inside a RichTextBox ?

I am Currently Using This Code :

Public Function Highlight(ByVal highlightcolor As String, ByVal ParamArray WordsToFind() As Object)
        'Loop through all the words you specified:
        For i As Integer = 0 To UBound(WordsToFind)
            RichTextBox1.Find(WordsToFind(i), RichTextBoxFinds.None)
            'Determine which color the word must become:
            Select Case highlightcolor
                Case "red"
                    RichTextBox1.SelectionColor = Color.Red
                Case "blue"
                    RichTextBox1.SelectionColor = Color.Blue
                Case "green"
                    RichTextBox1.SelectionColor = Color.Green
            End Select
            'reset the selection
            RichTextBox1.SelectionLength = 0
        Next i
        Return 1
    End Function

but it will only Highlight 1 of the word I set / Change the whole text into the selected colour

Example :

'I wanted to Highlight "Hello"
'I put this code into RichTextBox_TextChanged:

Highlight("blue","Hello")

'And It will Only highlight The First "Hello" inside my Text :

'Hello my name is XXX, Hello !

Any Ideas?

And, can I Highlight text between certain text / after certain text

Example :

'Highlight After the '

Or :

<!-- Highlight between these 2 tags -->

Please HELP Me !!