OK, here goes:
Tower of the Black Pearl: I set this in the Criestine town of Sparport Watch. Legends of the Tower are commonplace amongst both the townspeople and the pirates of the Wreckers.
Lair of the White Salamander: Thelport (not on the map) is a small town in Crieste, located on the small peninsula across from Halsgate Castle and just north of the Warderwood. It's a small town, with a population of roughly 2,000 - like most of those coastal towns in Crieste, it depends largely on trade and shipping. Because of its location, it's probably one of the best trading points with the Criestine colonies in the Southlands.
The Forgotten Sentinel: Also located in Crieste. See the nameless river just north of Sparport Watch? Just follow that river further north - at the source of the river, just west of the Blackore Hills, you'll find Lake Shadefell (not shown on the map), the abandoned town of Cortaigne ... and the Sentinel.
(Note: For the life of me, I couldn't find the name of this river. If it actually does have one, my apologies - if it doesn't, I'll make one up later.)
Well of the Worm: I placed the plains of Barrowdown between the towns of Marzakol and Iderag in Cinai. In my version of the DCC World, the adventure takes place in the small village of Thezarn ((population 400; not on the map), which is smack dab in the center of the plains of Barrowdown.
The Stench of Death: I set the town of Cold Harbour (not on the map) in the Kingdom of Luithea. It's a coastal town located on the peninsula just west of Cairnswild, and just west and south of the town of Welwyn. A town of roughly 4,000 settlers and sailors, the best way of reaching Cold Harbour is by boat - the few roads that stretch from Cold Harbor to Welwyn through the Cairnswild often fall prey to the undead creatures lurking in that haunted forest.
The Fate of the Vigilant: Set in the town of Fair Haven, which is in the Theocracy of the Lance - just like "Secret of Smugglers' Cove" and the upcoming "The Devil in the Mists".
The Crystal Shrine: Takes place beneath the Dunerain Mountains in the Kingdom of Uther, to the west of the town of Ironvale.
The Dripping Temple: Takes place at the hills at the base of the Ul Dominor Mountains, just to the north and west of Ul Gaolnor (one of the dwarven towns of the Holdfast of the Steel Overlord).
Please keep in mind these are only where *I* set these particular adventures - at this point, I wouldn't consider these locations to be official in any way. However, I hope that they'd be useful for any campaign set in the DCC World. If Joseph or Harley give them the Goodman Games Seal of Approval (TM), then that's another story, but unless that happens, just consider these the recommendations of a big DCC World fan ... who was also lucky enough to write and design parts of the world.
If anybody else wants me to provide a location for one of the other adventures from "The Adventure Begins", just let me know. Thanks!