Press P to open the PvP window. Here, you can sign up to join PvP Warzones and Battlefields. You can also keep track of which societies control each region.

Active World Domination Buff shows what buffs your faction is currently getting from PvP domination objectives.

The World Map allows you to switch between the available PvP areas by clicking on the icons.

Please note: Your character will NOT be flagged for PvP until you enter the Sheriff's Office in Kingsmouth. After entering the office, you will be able to begin the action using the PvP  window.