When you go you make a post, before you type anything, make sure you're in the HTML Editor, not markdown. Once you start typing you can't switch back and forth. There's a button to switch at the top right of the text box.
In the HTML Editor, you have the option to switch to editing the raw HTML code. This feature was temporarily removed, but it's back again. The button for "Raw HTML" is above the top right corner of the text box.
Steemit doesn't support all HTML coding, but you'll be free to do a lot more with your posts than what you can accomplish with markdown.
Thanks man. That was so weird last night there was no "raw html" button. I only had Editor and Markdown. Neither supported the basic stuff I was trying to do.
Weird. Maybe it's still glitchy. I wouldn't know since I mostly use markdown these days.