What are the exact steps of reporting a crime? If a PC is assaulted in town, would it be reasonable to immediately go to a guard? And what happens when you choose to 'call for backup' (I'm assuming a player guard is informed, though I'm not entirely sure)?

OOCly, what if the offending PC has already moved on (ran off after committing the crime)?

PC guards get informed immediately when you make a report. DM's get the report as well. Reporting immediately is a good course of action in many cases.

If you get a NPC to "call for backup," any Spellguard/Watch PCs within the confines of Dunwarren will receive an IC message alerting them to this. Any IG Dms will also receive a message.

Often times DMs are too busy to possess the guard, however if you're not getting a PC response you should feel free to send a DM message along the lines of, "*reports to the guard that such and such a crime has occured*"

If there's a griefer causing problems (i.e. attacking people randomly in front of non-possessed NPCs), a DM tell when you see it happening is encouraged so we can pop over and deal with them OOC'ly straight away.

If you can't get a response from either PC or DM-possessed guard, you might try IRC to get someone IG if it's an urgent situation or just send an IC letter using the Letters forum to the Watchhouse making a report explaining what happened.