Search function on the forum is broken, but you can use google to search, for example:
card game site:construct.net
I also suggest looking through Construct 2 tutorials, you may find something similar to what you need:
Search function has been implemented yesterday and is now working.
You can search through the forums.
If you encounter broken links, they are likely dropbox links their user did not update.
A card is nothing more than a graphical representation (so a Sprite object).
What you are looking to do is a bit like a memory match game.
You can check out this tutorial : https://www.scirra.com/tutorials/280/creating-a-memory-match-game
Searching the tutorials there should also work out for you. They were made for Construct 2, but since Construct 3 is built upon Construct 2, they translate well.