Slideshow

Hi janchemotti

welcome to the Apple (user-to-user) Community.

Re: how do I make a slideshow of some of the pictures on my Mac?

Wondering whether you want just a simple, straightforward method,

Eg:

How to: Create slideshows in Photos on Mac - Apple Support

Wondering where you want to use / play the slideshow:

How to: Export photos, videos, slideshows, and memories in Photos on Mac - Apple Support

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Else:

If you are looking for a more professional "presentation" type of slideshow, and are happy to download / learn how to use the software: Apple's "Keynote" software is available free from the App Store, if it is not already on your Mac:

https://apps.apple.com/us/app/keynote/id409183694?mt=12

How to:

Create your first presentation in Keynote on Mac – Apple Support

Keynote User Guide for Mac

Keynote - Official Apple Support

All the best :-)