Types, constants, variables and functions can be defined in the global scope by placing them in the global section labelled Declarations or System declarations, or locally for a template by placing in the Declarations section of a template.
Processes are instantiated by placing a process assignments in the System declarations section.
Finally, the system is defined as a parallel composition of a number of processes by placing a system declaration in the System declarations section.
The syntax for each of these sections is defined in the Language Reference.