Text block type
To change the way a piece of text acts, you can set the text block type to a certain setting.
Generally these 'text block types' wrap the text with a tag. These tags are then used by the site to match up style rules Ocular has written to that text, and style it accordingly. For example, you may want to make some text look like an h2 (header 2).
To do this, place your cursor (click) somewhere in the text you want to make an h2. You shouldn't highlight the text, just have the cursor inside it. Then, click the 'text block type' drop down box. It will most likely have the default of 'Paragraph' in it. You will see it dropped down in the image below.
After that, choose the type you want, in this case it will be "Heading 2". If you save the content and refresh the page in the frontend, you will see your text is now in the same style as all other h2's on the website.