Rolling the dice
According to your action, expertise, situation, and so on, the DM will tell you how many d10 you get to roll. With that information, you can roll the dice with the roll command offered by World of Warcraft:
You have to match the number of 9 with the number of dice the DM gave you.
Each digit is the score of a different die. You must get at least 5 on one of them to succeed. The more you have, the more significant the success. This can lead to critical effects, according to the DM.
You want to help someone to make sure an action succeeds or try to get a greater critical effect? That's easy, just say who you want to help and you can give +1d10 to someone's roll.