After you created a magazine you can add multimedia elements. One of those elements is the "Slideshow".
First go to "My publications".
Then click on the little pen icon to edit your magazine.
Go to the "Hotspot Editor" in the left sidebar:
Open "Enrich your publication".
You are now in the so called "Hotspot Editor". First choose the page you want to add the slideshow to on the right side of the screen. Then choose the "Slideshow" icon on the left side and drag the magazine open where it should be placed.
On the right side you can now see the configuration box of the element. Give it a title and choose the source of the images. In this tutorial we will choose Yumpu, which allows you to upload your images directly from your PC. Click on "Select Media":
Then click on "Upload files" and choose the images you want to use.
Now choose "Create gallery" and select all the images that should be displayed in the slideshow. Then click on "Create" and after that on "Insert".
Now you can also configure the rest of the settings like "Autoplay" and the "Border". Thats it!