messiah:script is based loosely on the C programming language.  Those users that are already familiar with C or C++ will find the language extremely easy to pick up.  Many of the more esoteric elements of C have been replaced with higher level mechanisms, so users new to programming will generally find the language easy to learn as well.

Users that are familiar with messiah's expression engine will also find the transition to messiah:script to be a fairly easy one, as messiah's expressions are a sub-set of the scripting engine.  For the most part anything that can be accomplished with an expression in messiah can be accomplished in messiah:script using the same functions and syntax (one notable exception is bracket expressions where the same results can be achieved, but with different syntax).

Compiling happens in two steps, first the preprocessor goes through and expands all directives, then the resulting text is then turned  into "byte-code". Now it is ready for execution. 

Note: The compiled version of the script is held in memory only, there is no compiled version saved to disk.

It isn't all that necessary that you understand how the script gets compiled, mostly you'll just want to be aware of the way the preprocessor works which is explained shortly.