I never found a tutorial of making particles, the way i learned to make particle scripts was modifying other people scripts and demos particle scripts, and using the Ogre3D reference manual.
You can get a few particle scripts in FeralHeart\media\particles
Also from
Ogre3D Demosa few examples (ignore the C languaje code):
Example Sun and
smoke effectOr even searching in ggole for examples.
Plus here is a reference guide to help to understand the code in scripts:
Ogre Manual