A default user folder (new install, or simply a new user) will not have an Applications folder, unless you either choose to make one, or an app install of some kind adds an Applications folder to your user folder, or you choose to make that folder yourself.
So, applications (the executable apps) will usually be in the Applications folder, or somewhere else, maybe in your own user folder.
And, most applications can be put anywhere on your hard drive, if you like (or if you need to do that)
If the app that you want to use is not in the Applications folder, then you will just have to search for it. Spotlight can help with that, of course.
And, if you know where the app is located, and you have some need to run it from the command line (terminal), then find the app, then drag it to the terminal. The app, along with the path to the app, will all appear in the terminal. Quite useful for doing "whatever" in the terminal.