Assuming your thread title is what you want the tab order to be (and not columns 1, 6,7) you can put this code into worksheet module.
To install the code:
1. Right-click the worksheet tab you want to apply it to and choose 'View Code'. This will open the VBE window.
2. Copy the code below from your browser window and paste it into the white space in the VBE window.
3. Close the VBE window and Save the workbook. If you are using Excel 2007 or a later version do a SaveAs and save it as a macro-enabled workbook (.xlsm file extension).
4. Make sure you have enabled macros whenever you open the file or the code will not run.
Private Sub Worksheet_Change(ByVal Target As Range)
Dim R As Range
Set R = Range("A1,A6,A7")
If Not Intersect(Target, R) Is Nothing Then
Select Case Target.Address(0, 0)
Case "A1": Range("A6").Select
Case "A6": Range("A7").Select