Welcome to ENWorld!
I'd recommend tuning into one of the live broadcasts of D&D games if you haven't already. There's Acquisitions Incorporated (
Dungeons & Dragons Roleplaying Game Official Home Page - Article) and Thursday Knights (
Thursday Knights on Justin.tv).
And I hear the Dungeon Master's Kit has a good adventure in it, if you're willing to start with a mini module.
The kids -- Mikael, Ricky, and their friend, the potential fourth player -- are veteran D&Ders, and have most recently played 3.5 together (in fact, they were griping about changes from 3.5 to 4), and have been in perhaps a dozen campaigns since their younger teen years. It's Tonya and myself that haven't gamed for almost a decade ... let alone run a campaign, which I've never done before.
Did one play a spellcaster in 3.5 and they're the most vociferous in griping about 4e? Or are they hardcore role-players and think 4e is like a video game? Those are the two most common complaints I've encountered.
Also be aware that I'd you're using the PHB, DMG, and MM "holy trinity", there have been substantive changes, e.g. the PHB has 22 pages of errata and monster design has significantly changed. If you've got some savvy players they may already be aware of this stuff, but keep that in mind.
main problem is that I've no idea what I'm doing as a DM -- from a mechanical perspective, that is. I don't really know how to structure the adventure so that it takes into account player choices,
I guess the tongue-in-cheek answer would be structure it less.
Roleplaying Tips for game masters has some solid articles about this sort of thing and much more in their DM articles archive. Another source I highly recommend is Sly Flourish; though Mike's advice tends to be for experienced DMs, he actually has an article about player choices...
Providing Real Choices.
Do you have a specific example of what you're talking about? I mean from the adventure you've begun creating?
don't know how to run encounters or what goes on during one from the DM's side -- though the DM Guide gives the basic ideas, it is short on examples
Those are things you'll learn as you go, we all had to, it's part of the learning curve. Best advice I can offer is that most of the time players won't notice when you make a mistake.
Again, any specific questions?
and am sort of gun-shy as to how to manage seasoned players when I myself am not only out of practice as a player, but completely green as a DM.
I've got two tricks for you.
First, recruit the players to make your job easier. Have one be I initiative tracker, someone keep track of treasure, another can help you clear maps/minis, maybe you can appoint a rules lawyer to help you out.
Second, listen to the players during "interlude" moments where they've got a decision to make. Usually seasoned players will theorize about plot secrets, or start devising strategy, or get into inter-party tiffs. Use that as fuel for your evil DM scheming.
So this is more the type of advice I need ... nuts-and-bolts campaign-building and running, with an eye to being adventurer-centric (and not too "narratively" inflexible).
Hmm. My parting words of wisdom are to read up on node-based adventure design and the 3 clue rule over here (links below). It's slightly advanced DM stuff, but you sound up for a challenge.
The Alexandrian - Node-Based Design
The Alexandrian - Misc Creations