3DCoat scripts are simple text files with AngelScript code
If you're familiar with C++, then using AngelScript will cause no problems. AngelScript code works very fast, that's why you may make pretty complex stuff.
It's good to use a text editor with syntax highlighter.
For instance, Notepad++ is a good choice. In "Syntax" menu choose "C++".
After creating a text file run it inside 3DCoat by choosing "Run Script" in "Scripts" menu.
What to start with? Start with primitives.