iPhoto upgraded to photos can't find my photos

The "iPhoto.app" in the Applications folder is only the program, it does not contain your photos.

You need to find the iPhoto Library, the database where iPhoto has been storing the photos.. The iPhoto Library should be showing an icon with a fan of three pictures, showing a pink blossom, like this. The filename extension (if visible) should be "photolibrary". If you did not move it, the iPhoto Library should be in the folder "Pictures".

iPhoto was discontinued 5 years ago. It is no longer developed or sold. It was replaced by the more powerful (and free) Photos.app that comes with the OS. You can migrate to that app very simply:

Hold down the option (or alt) key and launch Photos. From the resulting menu select 'Choose Library' and point at your iPhoto Library. It will do the rest.

If you prefer not to use Photos there are several 3rd party apps that you can use. Which to choose depends on the kind of photographer you are and your budget.

You want to find the iPhoto Library, not the iPhoto application.

Enter "iPhoto Library" in spotlight

Use Spotlight on your Mac - Apple Support

Does your iPhoto Library show in the finder? Did you move it to an external drive?

Have you tried using a Spotlight search to find it?

How did you upgrade to Catalina?