I see some posts that consist of multiple cards in a Gif of some sort. How do i post multiple cards like that.

Not sure myself I like to know how to do that as well. There not gif file types as Honey Select cards are png. The slideshow is a great way of showcasing your cards.

Those images are called APNG... you can easily make them online with https://ezgif.com/apng-maker. For a better outcome is better to use images of the same size