The Static HTML module has two different required text fields:
Title
This is the title that will show above the HTML module on the page.
HTML
This is where you would input your valid HTML for the module. Please make sure all tags are closed properly or you could possibly break your page. There are several great sites on the web to either get help with writing proper HTML, such as w3schools.com, or to help you validate your HTML, such as The W3C Markup Validation Service.
An example of proper HTML would be:
<p>Hello World!</p>