Using the compiler
You can download the latest compiler from the Download page.
To compile your Vellum script, put your script into a .vel file and run the compiler with the following command:
vellum.exe -f <path-to-your-script> -i <path-to-skyrim-scripts-folder>
If compilation succeeds, this produces a .pex file alongside your script.
Run vellum.exe -h to get info about other compiler options.