There are a couple "firsts" you'll need to accomplish before playing monster play. You must be a level 10 before your character becomes eligible for monster play. Once you're a level 10, you need to find a Fell Scrying Pool, which is pictured below. The Fell Scrying Pool allows you to "enter" the Monster play enviroment and choose a character. Keep in mind Fell Scyring Pools are located in East Bree, Michel Delving, and Thorin's Gate.
Next,
you'll click on the fell scrying pool and it will allow you to select
from several character options. There are several different monster
choices, a Reaver, Weaver, Blackarrow, Warleader, and Stalker.
You must select your favorite to enter the Ettenmoors and the dark battle that is taking place.
There's
plenty to do in the Ettenmoors, and your actions will often earn you
Destiny Points and Infamy or Renown (see below). Take on solo quests or
head out with a group of friends, looking for (and finding!) trouble.
Besides the smaller-scale battles you'll find yourself fighting in
while exploring the Ettenmoors, you can also engage in pitched battles
for the control of various points of conflict within the Ettenmoors.
A dynamic mapnote displays a flag - red for monster players and blue for Free Peoples - at these locations to show which faction currently controls them. Fearsome enemies or allies may await you within contested strongholds (depending on which side currently holds them), and you would be well advised to attack one of these locations only with a large force - but be on your guard! PvMP players might be defending their location, or attacking yours while you're gone!
You can then advance through the monster play ranks and devlop more and more, as it tracks your kills, deaths, killing blows, etc. It's pretty neat, almost a whole new character.