Minimizing compilation build time with parallel make

In the help, i can find:

2.21 Minimizing compilation build time with parallel make
If you are using a makefile-based build environment, you could consider using a make tool that can apply some form of parallelism to minimize compilation build time.

Even on a single machine with a single processor, a performance boost can be achieved. This is because running processes in parallel can hide the effects of network delays and general I/O accesses such as loading and saving files to disk, by fully utilizing the processor during these times with another compilation process.
If you have multiple processor machines, you can extend the use of parallelism with make -j N * M, where M is the number of processors.

Where i put the option '-j N * M' for make ?

Thanks