1)Start Microsoft Excel and open an existing workbook that contains cells you would like to hide the contents of, or start a new workbook and enter some content into a cell that you would like to hide.

2)Select the cells that contain data you would like to hide. You can select cells by clicking on them and using the SHIFT or CTRL keys on your keyboard to select additional cells.

3)Choose the "Format" menu and click "Cells" to open the "Format Cells" dialog box.

4)Click on the "Number" tab in the "Format Cells" dialog box to display the formats that can be applied to Excel cells.

5)Select "Custom" from the "Category" text box so you can type your own custom formatting to hide your selected cells.

6)Type 3 semicolons (;; in the "Type" text box to tell Excel that you want to hide the cells.

7)Click the "OK" button to close the "Format Cells" dialog box and hide the selected cells.