Hey @angelika.wronska ,
We don't have a guide. But, it would look something like this:
Create a Custom Type called "Slider" with an Image field "Main image". Then, create a group field, and inside the group field add an Image field called "Product Image".
Then, you'll link to the Slider document from another Custom Type, which I'll call "Page". On the "Page" Custom Type, create a Content Relationship field called "Slider".
In your code, you can use fetchLinks when you query the Page Custom Type to fetch the Slider data along with the Page content data.
If you'd like a more detailed example, let me know what technology you're using, and I might be able to create an example of the query and templating.
Sam