Without knowing which tutorials you looked at and found confusing, its a bit tricky to know where to direct you, but I'll give it a go.
To learn how the interface is laid out, and how to get around it, I'd recommend watching the Lab Interface Tutorials in the order listed here:http://fxhome.com/support/lab-tutorials/
Then, I would move on to the Lab Compositing Tutorials on that page, again, in the order listed.
For the most basic and simple explanation of creating a greenscreen composite, perhaps this article in the knowledgebase.
The more specific you can be with your questions, the easier it is to answer them. Are you having trouble creating a project? Selecting the right Project settings? Importing footage? Removing your greenscreen? Getting a cleaner Key? Making the layers of your composite match? Exporting the finished footage? More specific questions like these are easier to answer, as they give a more definite direction to go with an explanation.
Also, don't get too worried that it all looks a bit confusing at first. Digital video editing is a complex hobby, and even the pro's are continually learning new things. Once you get the hang of the basics though, you'll get get more comfortable with it, and will soon be experimenting with more advanced techniques.