On an iPhone:

Locate and press the SETTINGS icon, which looks like a grey gear, and then WI-FI. It will take a few moments to scan for available networks, but once you see the network you want select it and press JOIN.

Tip #1: To switch between numbers and letters, press the '.?123' button in the bottom left corner.

Tip #2: If you double-tap the shift key (up arrow on left side of screen keyboard), you'll be in ALL CAPS mode.

On an Android Device:

Method 1: Swipe down from the top of your screen and tap the wireless icon which should look similar to Image result for connecting to wifi android to turn on your wireless, if there are no saved networks in range it will display a list of networks you can connect to.  Networks that require a password will display a lock next to them.  Tap the network you would like to connect to and if required enter the password.  If successful it will show "connected".

Method 2: Pull down from the top of the screen and enter the settingsSettings app App and depending on your phone model find the WiFi settings.  This will give you a list of all networks in range and you will have the option to connect in the same way as method 1.

Note: Both Androids and iPhones will connect automatically to any networks they have saved the settings for so you don't need to do this every time.