This can be in the 'Macros' section of your 'Tools' drop-down menu or ribbon, inside the macro window (again, usually found in 'Tools'), or on a toolbar, depending on your version of Excel, your computer system, and your specific Excel setup. Macros can be run from a menu, connected to a button in the workbook, set to run automatically upon opening a worksheet, or tied to a keyboard command. This setting is in the 'Security' section, in most versions of Excel.
Steps Use Macros with Excel (Except for Excel 2008 for Mac)