This leads you to another page where you have to click on the Documentation button. 

Write the event name that you also wrote at step 5 and copy the url resource as seen in the image (only the part from the /trigger/ to the end)

Also, don't forget to change the name of your WiFi network and your WiFi password in the indicated fields. 

Save and upload on the board. if the IFTTT applet was created correctly, after flashing you should already receive an email. 

Have fun creating your WiFi buttons and don't forget to leave a comment telling us how it worked.