Embedding content on Tumblr is easy!
1. Copy the recommended embed code from the embed preview page.
2. Create a new text post on Tumblr then enable HTML editing by clicking on the 'HTML' button.
3. Paste your embed code and post.
Note: Your embedded content will only appear on your blog and not in Tumblr's subscribed stream of posts. (a.k.a. the dashboard)