Freeform roleplay does not mean anarchy. At the most basic level, all it means is that no stats and dice are involved - though that alone already implies a lot.
In most roleplaying systems, combat is decided by the roll of a dice. Your character has a certain rating in a certain attribute, e.g. '8 Strength', and a dice is rolled to add some randomness to that number before it is pitched against the stat of your current combat enemy.
Freeform, having neither stats nor dice, of course, has an entirely different combat system: Victim consent.
Freeform roleplaying is not competitive - it's more like playing in a theatre and improvising your way to a story than it is about winning x battles. As such, it's not that far-fetched to simply let the participants decide the outcome of the battle. You wield your weapon - your victim decides the outcome.
Why the victim? Why not you? Well, at all times, the idea of roleplaying together is to try to make it as fun as possible for all involvees. Destruction can be fun, but imagine if someone else had just decided your character dies. You'd not be very happy, would you?
Again, though, it should be stressed that freeform is not anarchy. No one can abuse their freedoms - that is what gamemasters are for. These are the wisecracks that watch over the game and make sure everyone plays fair. And that, really, is all they must do - though sometimes they're quite responsible for the plotline.
So, who are the gamemasters?
Glad you asked. Currently, the gamemasters are (by activity, then in alphabetical order):
These people's word is law. Try not to not question their decision on in-character events. Running to one of them about what another of them has 'unfairly done to you' isn't likely to yield success. They already talk to each other a lot and try to be consistent.
That's not to say you can't second-guess them, as long as you do it politely. They're still human - and they have an obligation to this game. They are your tools, keeping your environment friendly and consistent - they're not deities.
Note also: You can recognise them by their channel operator status in the IC channels.
Powerplaying and godmoding
The freeform combat concept extends to outside of actual combat. You should avoid describing another character's emotions or actions, unless they've been clearly and unmistakably established in their own last post.
A big no-no is trying to dictate another character's (however subtle) response to your own character's demeanour, actions, or statements. You can't enter a room and describe how every other character looks toward you. We'll cane your fingers for that sort of thing.
Nutshelled: Characters belong to their respective players. If you want to dictate their actions, get their express permission first.