In the upper right hand corner of the screen, near your mini-map (with handy red blotches that designate quest objectives), there is a button to queue for a Scenario. Obviously noobs will be overwhelmed in these situations, but it's only fifteen minutes and you respawn easily in the zone to just keep hacking away. There are also quest objectives for killing members of the opposing faction, and you get experience just for finishing the encounter.Of course there are plenty normal MMO quests (Kill wolves, find this dude, collect mushrooms...) but you can play any game for those. If you're coming to Warhammer, you're coming for the Realm vs. Realm and the Public Quests. Then, of course, there's the added bonus that even if you managed to kill just one guy, it still helps your realm in the overall battle.
Unfortunately, that vague knowledge is as close as we got to the huge scale that the war ends up taking. The highly anticipated sieges of "living cities" (that are more or less prosperous depending on how your faction is doing) are for those a bit closer to the 40 level cap.The Realm vs. Realm (or you could say, "epic PvP" with plural Ps) comes in many varieties from open RvR servers to zones within a "core" server, to specific instanced missions called Scenarios. Scenarios are great because they last just fifteen minutes, you get set up with a group as you arrive, and you can zap straight to one from anywhere.