In regards to your inquiry "please give me the code if the name of the sheets are "Grading 1", "Grading 2", and "Grading 3", are you asking how to get the drop down to list those sheet names, or how to modify the VB codes that I provided? The sheet names can be listed out in cells and then hidden (if using Data Validation). If asking how to modify the code, that is not needed, as it will go to the sheet based on the drop down value.
For placing the code, I am not sure how much work you have done with VB in Excel, so I will walk you through how to use this. For worksheet change codes, you need to place these into the Worksheet module(s). To get to these, beginning from within Excel, hit <b>ALT-F11</b>. From here, you are looking for your Workbook module, which looks like <b>VBAProject(My Workbook.xls).</b> Expand this using the <b>[ + ]</b>. Now you will see your worksheets listed out. Double-click on the worksheet where your drop down is located. This is where you will place the worksheet codes. The worksheet_change events only work on the worksheets where the code is located, no others. You can duplicate this code onto other sheets, but it is a one-for-one deal. Does this make sense?