OK so those are the Ads cards. You can access them via the Creatives tab (which appears in your second screenshot, but not the first one earlier). You can also use the Create new Campaign button on the main screen to start a new campaign and then click to the Creatives section of the process to create a card.
If the Creatives tab does not appear for you on ads.twitter.com, then you’ll need to click the Help link which is to the far right of the black bar at the top, and request assistance there.
These are our developer forums, so we can only help you with the cards that you embed on your own site, not the Twitter-hosted ones you create via the Ads dashboard.