If you're using Windows 7 you can use your snipping tool (a very useful device). The only problem is that it will only copy one screen at a time so if it's a LONG document that won't be very practical.
I use it regularly to save things I want to keep for Daizy to see. It's very convenient.
Just remember that if you save it as a .jpg you won't be able to edit it as a document.
This will highly depend on the type of document you have at hand. If it's a Word document, it will be easier to use a Snipping Tool. From the Start button in Windows, go to All Programs, Accessories and select snipping tool. Drag it to the Word document, then save it in the desktop.