You can create your own player events with the calendar. Set up small events like a dungeon run, or larger events such as a raid or guild meeting.
To create an event, right-click any current or upcoming calendar date. The standard "Create Event" option will always be available, and another option, "Create Announcement," will also be available if you are a member of a guild and have the proper permissions.
When "Create Event" is selected, a new event window will pop up to the right of the main calendar window. An empty field for the event's name is the default selection. Along with the name field, you can designate the starting time, the category, and a description of the event. The available categories for events are Raid, Dungeon, PvP, Meeting, and Other. These categories help those you invite quickly identify the nature of the event (with Other being a catchall category) and are accompanied by custom background art (for raids and dungeons, the art is specifically matched to the individual raid or dungeon).
Below these fields is a list of the invitees and their status. If you have just created the event, the field will be empty. Enter the name of a player you wish to invite, and then hit the "Invite" button. Repeat this process until your list is complete, and then press the "Create" button and your event will appear on the calendar's date entry - and the invitees will immediately receive notification of the event.
There is an additional filter that allows you to invite multiple people in your guild or Arena team without manually entering each name. This filter, called "Mass Invite," can be found at the lower left of the main event window. It automatically invites guild members or Arena team members in order to make creating these kinds of events quick and easy. For example, the event creator will be able to automatically invite everyone in his or her guild who is of a certain level (or level range) and of a minimum rank. After accepting, you will be sent to the normal event creation window with the invite panel pre-populated with your invitees.
If you are a member of a guild and want to quickly invite everyone in your guild to an event, you should choose the "Create Announcement" option instead. This event type is designed for guild officers (or those in the guild with the proper permission) to invite every member of their guild to a large-scale event, such as a guild meeting, a city raid, or anything else that would lend itself to an entire guild's attendance. It is also intended to be used as a quick and easy raid scheduling method for more informal guilds. There is no additional filtering allowed on this type of event, so make sure you actually want to send this event to everyone in your guild before sending it out.
Once created, an event can be duplicated by right-clicking it and selecting "Copy Event," then right-clicking on a new date and selecting "Paste Event." This opens up a new event window and automatically transfers over all the fields except the event time and the lockout settings. The list of invitees (whose status is automatically set to "Invited") is copied as well. Once an event has been copied, it can be pasted repeatedly on different dates. In this manner you can create recurring events, such as a weekly Zul'Aman raid or set of 5v5 Arena matches with the same group of people.