open the game with -tools as launch command. At the top you can somewhere select the "particle viewer", now click open, click the .pcf and it should load a list with all particle effects in the pcf. You can preview all of them, and even edit them if you want.
Copy the name of the effect you want in your map and use the name for a info_particle_system. Give the info_particle_syste, the "start" input to start the particle effect if you use the "spawn disabled" property.
I'm not sure though if you can just grab a particle effect from gmod, especially if it wasn't made to be placed in a map, but just go ahead and try it out.