Here is a quick reference before we get started. 

When Airplane Mode is ON wireless is OFF
When Airplane Mode is OFF wireless is ON
When Airplane Mode is ON the network icon will be an airplane

Step 1 - Look for the network icon in the bottom right corner and click it. Along the bottom of the window will be a button for Airplane Mode.

Step 2 - In this case Airplane Mode is on and we want to turn it off so we can enable Wi-Fi. Click the Airplane Mode button then click the Wi-Fi Button. You should see this if everything switched correctly.