picma is a "compassempreter", an unholy blend of a macro assembler, a compiler, and an interpreter. It reads picma source files, and creates various output formats, suitable for writing into a PIC.
You need some hardware too, if you want your code to end up inside a PIC. A suitable programmer and other useful bits will appear here when it is ready.
Here is the documentation for the picma compiler and
The compiler archives are available here: