The About section of your campaign is the main area where you describe what this campaign is all about and is your chance to tell your story to engage your audience to become supporters. It appears on the About section of the Hosted Campaign Site, as well as on the About page of your Integrated Campaign from the menu (but generally is not easily seen on Integrated Campaigns, so keep this in mind).
To edit the “About” section of your campaign, go to the Edit this Campaign for the campaign in question, and click on Campaign Settings. Click on the Title & About section to expand, then type your text in the text editor. You can also add photos, videos, and change the formatting of the text. Don't forget to click save when done. You can preview your changes by clicking one of the preview options at the top.