Edit the pad on the right to build your HTML page (click the Create Pad button if necessary). Here's a simple page you can copy-and-paste into the pad to get started:
<!DOCTYPE html> <meta charset="utf-8"> <title>My First Web Page</title> <p>Here is my first Web page!</p>
Once you've written something, you can view your page at htmlpad.org/oh-newsletter-201501/.
Saving happens automatically, so don't worry about that.
Keep switching back and forth between the editor and the view to rapidly iterate on your design. Give the editor link to a friend if you'd like to collaborate in real-time!