Welcome to the world of 
@Wildfire!
There are lots of super simple ways to get started with the Core! You do not need to be an expert in web programming. We are really proud of the fact that this community comes from vastly different areas! Some people are professional web developers but don’t know anything about electronics; other people like yourself are pretty familiar with Arduino, but are a bit intimidated by the whole REST API thing. Luckily, we all work together to help each other out!
First, you can use our mobile apps to tinker with your Cores—the app makes the REST API calls so you don’t have to worry about it!
Next, when you write your own Arduino code, some folks here have contributed simple web interfaces for checking variables and calling functions. Check out this thread:
When you’re ready to write a little code yourself, just start with the simple one liners from our Cloud API documentation. They use a program called “curl” that might even be already installed on your machine.
And of course, as you start making that greenhouse project, you can always ask for help here in the community. Lots of people here very willing to help troubleshoot your web-facing code.
Again‚ welcome!