As you continue to add to your worksheet, sooner or later you will need to insert columns and rows within the areas where you’ve already added values. You can easily insert a column—or more than one—and add rows, as well, and if you’ve inserted formulas on the worksheet, Excel 2013 will adjust the formulas automatically to accommodate the addition of the new cells.
Right-click and hold the column header immediately to the right of where you want the new column to appear.
In the options menu or minibar that appears, click Insert.
Right-click and hold the row header ...