I would say plan an adventure how you would normally, only thing in PbP, combats take a bit longer so I find it's better to have fewer, more difficult encounters than frequent n or n+1 encounters. Treasure is handled via the DMG recommendations here so as long as you're cognizant that XP is doubled, therefore treasure should follow suit, you're good to go.
Adventures are sent into the judges account you sent your PC request to. As an FYI, there's currently a few adventures approved without PC's, but that problem may be alleviated when PHB3 becomes approved in a month or so. Personally, I'd suggest holding off until you've played a bit to make sure you like the pace of PbP, it's a much different animal than tabletop gaming.
[sblock=Charter info]
http://www.enworld.org/forum/living-4th-edition/246934-l4w-charter-read-first.html
Dungeon Masters
A Dungeon Master of some kind is necessary for any adventure, even an extremely short vignette. In order to start an adventure, the DM must request that the current judges in charge of adventure approval approve the adventure. Any adventure needs to submit the following information in order to be approved:
1) Who are the players: This can be a specific list or this can be a description of what kinds of characters are likely to fall in line with this adventure. DMs are strongly encouraged to offer openings to players that not already has a character on an adventure.
2) What is the story: What is the story of the adventure itself? What are the events that lead up to How is victory achieved or defeat met?
3) What is the background: Describe the setting, the people, and the motives that make this adventure.
4) What is the challenge: Specifically, what encounters, skill challenges, and roleplaying challenges will the players encounter? You don't need to completely spell out every encounter, but you should indicate where in the adventure the encounters lie and give a basic description and indicate how difficult they are meant to be. Example: "After defeating the animated waterbed, the PCs must escape the haunted boudoir by fighting their way through a series of trapped corridors while spectral French maids emerge from the walls and pursue them with diseased feather dusters. This encounter will be 2 levels above the PCs level".
5) What are the rewards: What kinds of rewards are there to be found? Fame, money, magic, and experience should all be expressed here. Anything that can be a reward is important for the judges to see. At a minimum, describe which treasure packets and the total amount of experience from encounters that PCs can get.
6) How long is the adventure expected to be? E.g. a long campaign, a medium length adventure, or a short vignette with only a few encounters. DMs new to play-by-post gaming are strongly encouraged to run a few vignettes and short adventures before trying their hand at a longer game.
The things we're looking for in an adventure proposal are basically as follows. First, to make sure that the DM isn't planning anything too unbalancing or destructive, like handing out a bunch of +5 vorpal swords to level 1 characters or having an army of undead dragons invade Daunton. Second, to make sure the judges have enough information about the adventure that if the DM were to suddenly disappear, a judge or substitute DM can step in and finish the adventure. Third, to make sure that any new setting details or NPCs you introduce are compatible with the rest of the living world's setting.
Submitting an adventure proposal does not mean that a DM can't improvise. No plan survives contact with the enemy, and no adventure outline survives unchanged once the players start posting. DMs are expected to use their judgement and adapt to player actions throughout the course of an adventure, and there is no need to re-submit if a DM changes plans in response to players.
DMs are not as limited as players in terms of what sources they may use. Feel free to use monsters from non-approved sources, or custom monsters, as long as they fall within the DMG's guidelines for customizing monsters. When in doubt, consult a judge. The exception is items; if you intend to have items in your game that might possibly fall into the players' hands, they should either be from approved sources or you should clear them with a judge first.
When an adventure is approved, then the DM can begin recruiting if necessary. The Hanged Man Tavern is the usual place to go to find a party of adventurers, though the DM may arrange a different beginning by discussing it out of character in the discussion thread. The DM need not take all comers, they may choose as they see fit from among the characters who express interest. As mentioned previously, DMs are strongly encouraged to offer openings to players that not already has a character on an adventure.
After the adventuring party is formed, the DM needs to find a judge that is not playing in that adventure to watch the adventure. This judge has the responsibility to step in if the DM disappears, and can override the DM if necessary. (This should be very rare, and would only happen in response to abuse by the DM.)
After the adventure is completed, the DM will give final awards for experience and treasures, and resolve how the PCs leave the adventure if it is site based. If there is an option for a continued adventure, it is important to plan for some players to be able to leave and for new members to join a group, because this is the nature of the forum.[/sblock]
