upgraded to Catalina. What do I do about IPhoto

You can open your iPhoto Libraries in Photos for Mac to get access to your photos.

If you just have one iPhoto Library it should suffice to drag the crossed out iPhoto.app onto the Photos icon in the Dock and Photos will create a new Photos Library from your iPhoto Library. If you have more than one iPhoto Library, use the method described here:

Updating from iPhoto to Photos for macOS – Apple Support

How Photos handles content and metadata from iPhoto and Aperture - Apple Support