The facebook API is probably the friendliest and best-documented "web API" out there (which is not to say it's good, and they're terrible about changing it all the time - but compared to their competitors...). Their docs have examples, and also the interactive "graph explorer" is a very good place to play around to start with. You edit code the way you normally do, and your code makes web requests to their APIs. If you're not comfortable with that, maybe some tutorials on e.g. web scraping (that's a popular thing to do in Python) would help you get more comfortable with doing HTTP in Python? Or from the other edge, try making the necessary HTTP ("REST") requests to facebook "by hand" using something like Postman, and then writing code to do that.

As others have said, start with a "hello world" and then add features to it.