For most apps, if they're compressed with Stuffit, uncompress them first, otherwise simply double-click them. They don't need to go into any particular folder; you can put them anywhere.
Some complicated apps may have an installer that you'd double-click as you would with OS X. These have installers because some files might have to be placed in the Extensions folder and elsewhere. IE running in later versions, up to and including OS X, littered the drive with files.
If an app is on a floppy, drag it from the floppy onto the desktop or into any folder.