Option Explicit

      Private Sub Command1_Click()
        
       HighlightWords RichTextBox1, "Kırmızı", vbRed
        HighlightWords RichTextBox1, "Mavi", vbBlue
      End Sub

      Private Function HighlightWords(rtb As RichTextBox, _
                                  sFindString As String, _
                                  lColor As Long) _
                                  As Integer

        Dim lFoundPos As Long           'Position of first character
                                        'of match
        Dim lFindLength As Long         'Length of string to find
        Dim lOriginalSelStart As Long
        Dim lOriginalSelLength As Long
        Dim iMatchCount As Integer      'Number of matches

        'Save the insertion points current location and length
        lOriginalSelStart = rtb.SelStart
        lOriginalSelLength = rtb.SelLength

        'Cache the length of the string to find
        lFindLength = Len(sFindString)

        'Attempt to find the first match
        lFoundPos = rtb.Find(sFindString, 0, , rtfNoHighlight)
        While lFoundPos > 0
          iMatchCount = iMatchCount + 1

          rtb.SelStart = lFoundPos
          'The SelLength property is set to 0 as
          'soon as you change SelStart
          rtb.SelLength = lFindLength
          rtb.SelColor = lColor

          'Attempt to find the next match
          lFoundPos = rtb.Find(sFindString, _
            lFoundPos + lFindLength, , rtfNoHighlight)
        Wend

        'Restore the insertion point to its original
        'location and length
        rtb.SelStart = lOriginalSelStart
        rtb.SelLength = lOriginalSelLength

        'Return the number of matches
        HighlightWords = iMatchCount

      End Function