All events, for all regions, should appear here: http://nzlarps.org/events/. They appear in other places on the sites too, but the main place they live is under the events section. The exception is monthlys which, for now, live on the homepage only. That is likely to change in the future, so they are at least mentioned in the events section.
Diatribe is split into categories, so if you know which category you want to read or post to, you can use the category view. The latest view is easier if you are a frequent user (more than once a month). There's also a pretty good search function if you are trying to find something in particular.