There's loads of ways you can do it.
The above poster showed one way. Another way is the same, but instead of typing it like a story, you type it like it's actually you, so it'd be
*Walks over to xYoMommax/Chris* (Username or charactername)
Hey, dude, when are we gonna get going? I hate waiting!
*Turns around*
Don't worry Donna, we'll be leaving soon, I just gotta sort..
..Etc etc.
The way I do it is a mix of both. Mine is more like Pen&Paper roleplay, but online rather than in person, and it's me doing all the dice rolls. As the Game Master (GM) I tell the story, and the players have to react as their character, also telling me what they do about the given situation eg:
GM: You turn left and walk along the unlit hallway, only your flashlight beams breaking the darkness. Ahead, you hear a scream..
Character 1: OMG! (I turn to face the others) What was that?! (Cowers)
Character 2: Don't worry! I'll go check it out! (Starts towards the scream)
I might then decide that I don't know if the character would make it far, so using the character's stats, I would roll dice to see if the character was successful in the action, and then carry the story on from there, eg:
GM: Okay, I roll a Composure+Wits for Character 2. It's a failure, you only make it a few meters before the darkness envelopes you and you hurry back to the group.
Character 3: ****, what's going...
..etc, and it goes on from there.
It sounds hard but it's fairly easy once you get the hang of it, it's just acting in character, but following the in-game-guidelines you're given by the storyteller
And the character stats you make yourself before the game using a character sheet, which I can explain more about if you join in a game, cause otherwise it's a waste of brain-overlode