Include rich content on your Tumblr blog with Cards
One
First get the Card
If you have already copied the embed code, skip to the next step. If you haven't, you must do that first. Paste the web page URL in the Embed Code Generator, and copy the embed code.
Two
Now post it in your Tumblr blog
Add a new post.
Click the '<html>' button in the editor. Paste in the card code.
That's it! Go ahead and save the post.
The Embed Button for Tumblr
Make it easier for your viewers to get Cards for each of your posts - Add the Embed Button.