By default, you should be able to open an XLSM file without an issue (as long as you're using Excel 2007 or later), but the macros normally aren't enabled by default.

An Excel Workbook 2007 or 2010 business file enhanced with macros will have the XLSM file extension. If you have Excel 2007 or 2010, double-click the filename to open the file.

Click the File tab (or Office button) and choose Save As. Choose a location as necessary. From the Save As Type drop-down menu, choose Excel Macro-Enabled Workbook (*.xlsm). Figure A ...