Some things to note:
- When I wrote the guide, Dialogflow was still called API.AI
- I wouldn't suggest the approach I used for the Wimbledon Finals bot for understanding how entities work
- I now have a better understanding of how training phrases affect the behavior of the agent, so the vending machine bot wasn't built properly
- My views on follow up intents have changed quite a bit
- I didn't really cover webhooks in any detail in the old guide
My recommendation would be to instead go through this detailed tutorial (especially if you are not a programmer, or if you are a programmer new to Dialogflow).
If you are still interested in the old tutorial for some reason, you can purchase it here.