From the main screen;

Select Settings

 

Wireless & Networks

Turn Wi-Fi "On".

Available Networks will appear on the right portion of the screen.

These are the available networks, here you find the network you want to connect to.

Select; the Wi-Fi network you wish to connect.

 

 Wi-Fi

you will see : Signal Strength, Security Type

Enter Password Key:

Check the box "show password" to verify your entry.

Select: Connect