On my laptop, the switch is actually on the outside. It is located on the left side of the computer in the corner closest to you.
Go to the control panel and set the properties of the wireless switch. You can make any changes here. You can either turn it on or off. You would also have to configure Wireless Network setup in the control panel.
IT's depends on your model. In my laptop I turn on it by pressing fn+f1. See there will be icon of Wireless on laptop keyboard
It all depends on the make & model. One of the least standardized items in the industry, so you have to be a specific about you computers make and model as possible. It may be a hardware switch or it may be a key combination (ie Fn+F2)