Now that you are aware of all the GPIO capabilities, you can start putting them to work. In order to do this, it is best to purchase a small breadboard and some jumper wires; this will make connecting to the outside world easier. Here is a picture of such a breadboard:

They are easy to find, you can purchase one at almost any electronics store, or on any electronic online sites. You'll need some jumper wires to connect from the Galileo to the breadboard. The jumper wires you want are the Male-to-Male solder-less jumper wires. Here is a picture of this sort of wire:

These jumper cables plug easily into the header pins on the Galileo and the breadboard. Now that you have the cables and the breadboard, you can start accessing and controlling hardware.