Hey there, sfvaughan. 

Don't worry, I've got you covered, follow these few steps to copy your data from the Excel file to the IIF file: 

1. Open an Excel file.
2. Click File in the upper-left hand corner, then select Open.
3. Click Browse and look for the IIF file.
4. Select the file and click Open.
5. If you can't see it, make sure that you select All Files in the lower-right hand corner.

I'm also including a very helpful tool that gives you an overview of the IIF files, check it out. 

• IIF Overview.

If there's anything else I can help with, please post down below. Thanks for your time and have a nice day.