Rez it on the ground and the particle effect will start.
Type "/66change" and a menu will drop down allowing you to choose 12 types, 12 colors, 3 sizes, 3 speeds, 3 radii or turn the particles off.
Caution: If you choose "finalize" in dialog box then the type, color, size and radius is fixed. (even if you type "/66change", dialog box won't drop down)
You can also use voice commands on channel 66, as follows:
/66 on_off /66 finalize /66 default /66 flower /66 rose /66 star1 /66 star2 /66 star3 /66 butterfly1 /66 butterfly2 /66 fire /66 heart /66 snow /66 leaf /66 small /66 medium /66 big /66 slow /66 normal /66 fast /66 narrow /66 middle /66 wide /66 white /66 gray /66 black /66 blue /66 red /66 green /66 yellow /66 pink /66 cyan /66 magenta /66 lavender /66 rainbow
Texture: /66 texture UUID - UUID is the UUID of the texture you want to use. To obtain that key, find the texture you want to use in your inventory, right click it, and choose 'Copy Asset UUID', and then ctrl+v, it'll get you the desired key. The command will look like this: '/66 texture c6dbc4b2-918c-b224-8f8d-210b9a07fabf' If you choose "default" in dialog menu, it will revert to the default texture.
Size: /66 size VALUE - changes the size of the particles, range 0.03125 - 4.0. (default size is small - 0.5, normal - 0.8, big - 1.1) The command will look like this: '/66 size 0.1'
Rainbow Color Interval: /66 time VALUE - changes the color change interval of the particles which it choosed "rainbow" in dialog menu. (default interval is 1.0) The command will look like this: '/66 time 1.0'
Radius: /66 radii VALUE - changes the distance from center of the particle emitter. (default radius is narrow - 3.0, middle - 6.0, wide - 9.0) The command will look like this: '/66 radii 3.0'
Speed: /66 velocity VALUE - changes the speed of the particles, range 0.0078125 - 100. (default speed is -1.0) The command will look like this: '/66 velocity -1.0'
Time duration: /66 age VALUE - changes the time duration of the particles, range 0.1 - 30.0. (default length of time is 3.0) The command will look like this: '/66 age 3.0'