There are two ways to switch on the wireless adapter and the first is to go into the network and sharing center and select change adapter dsettings , this will open the adapter page and you should see your wiereless adapter and by right clicking on it you will see an option to enable it. If you do not see your wireless adapter then the drivers have not been loaded and you should go to the Dell support web page and enter in your service tag number and it will bring up your computer and all that's in it , you will then be able to select a driver for the adapter that's in your computer.
Second on the keyboard there is a Function key (Fn) and that enables the second set of letters and symbols that are on the keys (they will be a different color) and you want to look for the key that has the little wireless antenna on it and then press the Fn key and that wireless key at the same time and that will activate the wireless adapter.