There is this website called logmein.com. LogMeIn is a large on-line remote desktop provider that allows to to remote control computer from across the world. They have professional packages that include sound and file sharing but you have to pay for a subscription to those. What I am going to show you is free but doesn't have all of the cool features but it still allows you to remotely control any computer.
First you are going to need to create an account at LogMeIn. Just
click here to be directed to the sign up page. When you go to that page there will be an option to start a LogMeIn Rescue account or to just start a free plain account. You are going to want to select the first option and click continue. Then you will be asked for some information. Fill the forms out with valid information, you don't have to worry about spam or anything because LogMeIn is a very safe and secure site.

Image via
Wikipedia
Once you have created you account and confirmed it you will now be able to add a computer. If you would like to add your computer so it may remotely connected to, select "Add This Computer." Go through the setup and install the software and adjust the setting to how you want them. Once that is all set up you will be able to log onto LogMeIn from any computer in the world and as long as the main computer is on you will be able to connect to it and control it.
Once you have the main computer you want to control added you are able to add other computers. You can add many computers. I find this software use full if you are running some sort of home server and you need to access it from a remote location, you can just log onto LogMeIn and control your computer. Another way to use this would be if you have older people in your family that are not very good with computer. You can go over to there house one day and install the software and now whenever they need computer help you can just log onto there computer and assist them with whatever they may need.
I hope you found this interesting and have fun playing around with it! If you have any questions or need help setting this up please feel free to leave a comment below with your question or just sending me a message!
Have Fun!