How to Create an Excel XLA Add

1. Launch the Microsoft Excel software. Click 'File' in the top navigational bar and select 'New' from the drop-down menu. A Workbook Options window will be displayed. Press 'Blank Workbook.' Excel will create a new workbook.
2. Select 'File' in the top menu again. Select 'Properties' from the drop-down menu. Look in the Document/Name Properties box and press the tab labeled 'Summary.' Name the new workbook. This name will be what is shown in the add-ins window after you are finished.
3. Click 'Tools' in the top menu bar and select 'Macro'; then click 'Visual Basic Editor.' The editor will appear on the screen.
4. Click 'Insert' in the top menu bar and click 'Module' from the drop-down menu. A code module box will be displayed. Enter in the function code with which you want the Excel add-in to work. For example, you may type 'Function' followed by a space, then 'Age(DoB As Date).' This add-in, if activated in an Excel worksheet, will convert any references to DoB to the numbers listed in the Date column. If you are unsure of how to structure a function code, browse the Microsoft Excel help site (see Resources).
5. Save the file. You may now add it to a current worksheet by selecting 'Tools' in the worksheet and choosing 'Add-Ins.' Navigate to the hard drive folder in which you saved the XLA file and click it; then press 'Open.'