Greetings from Viovio!
You will need to make sure that the image resolution is 300dpi on all your images. If you downsize anything the results will be a blurry image. You'll also need to make sure that if the image is intending to go on, example, an 8.5x11 page that the image itself will need to be at least 8.5x11 or it will need to be stretched in order to accomplish this size. The Understanding resolution page does a great job of breaking this down! http://www.viovio.com/wiki/Understanding+Resolution
We offer an auto-fit template that also might help you out! You can view it here: http://www.viovio.com/designer/template/799 Auto-fit will automatically fit your image within the template.
You can learn more about cropping images here, if you are concerned about this: http://www.youtube.com/watch?v=8otP3TzxOkw&list=UUgWmJwU2t0SRxjGkHaEVzGA&index=6&feature=plcp
You can save the word file as a pdf or jpg, upload the pages and then drop them in as images if you'd like.
You also have the option of using our captions option, then copy and paste the text as a large caption. Here's a helpful screencast that will show you more about this: http://www.youtube.com/watch?v=CcATwwU9KJY&list=UUgWmJwU2t0SRxjGkHaEVzGA&index=7&feature=plcp
If you have any further questions please don't hesitate to ask and we'll do our best to help!