Quoted from canea:
I usually just print them at an online photo place as 4 by 6 pictures and then trim off the extra space on the top and bottom, maybe a hair off the sides. Usually works pretty well.
Exactly. When you double click them, they should open up with Windows Photo Viewer.
Top left click print. Choose 4x6 paper size. If you have some nice glossy photo paper, they look amazing. just make sure to change photo type to "Glossy Photo Paper".
You'll need to trim the length and height slightly as mentioned by canea. Maybe an 1/8th of an inch on each side.