There is a search tool to find files on a Mac. The search itself has different names depending on your operating system. In the most recent OS Mojave it's called Spotlight. Just look for the little spotglass in the corner of the top of your screen.
As a tip, if the disk your OS is on has a huge amount of space just use the file system Apple has created. Don't go creating and sticking files everywhere. Your system will run more smoothly. If the disk your OS is on is small create a file system on an outside our second internal drive that is well organized and place a few key folders on your desktop. Be neat. One thing that used to distinguish Mac users from PC users was that Mac users had clean organized desktops.