Computer to computer is just a way to share files between computers, I am not sure if there is a way for this to actually share an internet connection. The other computers connected to this can access your "shared documents" folder sometimes, and opens up a way for them to hack into your computer. So if it looks like a signal that says "Free Internet Access" is coming from a laptop, be wary...

Also, be sure your wifi is turned off when onboard an aircraft. Many times have I seen other users with their wifi on during a flight. Although it shouldn't cause problems, it just isn't good to do.