Here's how the dice roller works: The command is : dice xdz : without the spaces between the colons.
The command : dice 2d6 : (without the colons) would roll two 6-sided die. Like so:
Rolling 2d6:
(1+5): Total = 6
Sometimes you may need to add or subtract to the dice roll, for instance you may need to roll two six-sided die minus one. To do this, use the command : dice 2d6-1 : (again, without the colons). To wit:
Rolling 2d6-1:
(2+3)-1: Total = 4
If for some reason you want to hide your roll, for instance, you want to pickpocket a fellow player (what a jerk!), just add "spoiler" tags from the above commands -- it's the button with the hazard symbol. This would work like so:
[spoiler]I stealthily pickpocket Cynthia.
Rolling 1d10:
(6): Total = 6
[/spoiler]