Locate and click on the ‘Settings’ icon.
Click ‘Network & Internet’.
If the WiFi is ‘Off’, click the switch at the right hand side to turn it on. If you are within range of a network you have previously used, your phone may connect automatically. 
If not, a list of available networks will be displayed. Click on the name of the required network.
Type the password. (Click the ‘Show password’ box to check you’ve typed it correctly.)- Click ‘Connect’.