How do I save to a folder in my dock?

As the Dock is not an actual location to store files, more like a place to put aliases onto (alias = shortcut), you can't actually save something to the Dock.
But the folder you dragged onto the Dock is still in the place you dragged it from, therefore using the SAVE dialog should allow you to navigate to the actual location of the folder, which is NOT the Dock.

 

Just drag and drop the folder you are trying to access to the dock and then it will show up there.

 

1. You create a folder anywhere you want. For example, create MyFolder in your Documents folder.
2. You drag that folder to the Dock, creating an alias (shortcut) on the Dock that points to that folder.
3. You can save files to the /Users/yourusername/Documents/MyFolder, or you can drag and drop items to the Folder icon on the Dock. Either way, it all ends up in the same place.
4. You can open the folder from Finder or from the Dock.