In case of contact with computer or laptop in the coverage area of the wireless network and availability of wi-fi connection (home, apartment, hotel, airport, cafe, Park, etc.) it usually finds the network. This can be understood via the activation icon in the bottom right of the screen. It becomes more bright and slightly flickering.
If the network is free, the Internet connects automatically. If not, try clicking on the icon and select "Wireless & networks" in the appeared menu. Usually this displays a small list of wireless networks, the source of which is nearby. But most of them are protected by the access code, as evidenced by the key icon next to the name. If the access code is known, enter it, and the rest of the computer will do it myself.
If you assume that the network is free, but connection is not happening, then you should contact your public place where you are. Typically, such problems arise in airports, railway stations, cafes, restaurants and other public places.
Sometimes, the computer was able to successfully log on to the Internet via wi-fi, but you still can not get to the desired email address. Just try to start the browser. You may see a page with the prices and the payment methods. Please review them and contact the appropriate service to charge for access. This practice is often used in hotels.
The access key is usually entered once. Next time when your computer will be in range of that network, the connection will happen automatically, provided paid bills, of course.
To disconnect from a wireless network is not required, the computer will also do it myself, once out of its zone of action. Yourself this can be done by clicking the wireless connection and click "Disconnect". In addition, it is possible to disconnect via the menu "start" -> "Connections" -> "Disconnect".
Disadvantages of connecting via wi-fi is the lack of access points (hotspots) in small towns and other settlements. Typically, this can boast only of a large city and Grand Central airports.