Headings help make your content easier to read and assist search engines in determining the important content on your site. To make a heading make sure the second row of tools are showing in the post or page editor by clicking the ‘Toolbar Toggle’.
In the text editor highlight the text you want to make into a heading. Click the text formatting drop-down menu. By default this is set to ‘Paragraph’. Scroll through the list and select the style you are looking for.