@Dersarius: The example that @matt_thomas posted is a full function that adds the file_get_contents_curl function. You would need to include his entire function in order to then use file_get_contents_curl($url). Right now, you’re not including the function (that I can see) and you’re just calling cURL($url), which isn’t the name of the function.
Having said that, you should really just learn how to use cURL. That will help you immensely in the long run for all APIs if you’re going to use PHP. Matt’s abstraction is a huge help, but you should understand what it is doing. If you’re new to PHP, I would recommend PHP The Right Way or PHP on CodeAcademy.