A macro is simply a programming script that automates software functions to speed applications. When opening the TNT, you should expect to see this dialogue box open prior to the TNT loading:
This is completely normal, simply select "Enable Macros" with your mouse.
Demystifying Macros - a simple video:
If you see this message:
Then Excel has been installed on your machine with a high security setting. To change this, follow these steps:
1) Close the TNT file and Excel. Then re-open Excel.
2) From the tools menu in Excel, select "Options", then select the "Security tab", then the "Macros Security" button, select "medium" from the list. Save these settings by clicking "OK" and then "OK" again on the boxes. You are now ready to use the TNT.