Each document must be 15 mbs or less.
Scan (or print to pdf) each document separately and save it on your system.
Go back to that directory and right click on the document.
Click properties. The screen will show you the size of your document. If the document is within the 15 mb limit, you may attach it to your entry.
If the document is larger than the 15 mb limit, you will need to break the document down into separate documents before attaching them in your entry.