Normally the Applications folder that is in your Dock is the one at the root level of your hard drive. To see it, open up your Hard Drive (not your Home folder) and you should see something like:
Applications
Library
System
User Guides And Information
Users
That Applications folder is the one where all Applications (for all users) lives and is the one that's in the Dock. Sometimes a user will have an Applications folder in their Home folder but it will only contain Applications that are specific to that user and generally is not the one that is in the Dock.