Noir includes the option to add an author bio that will appear at the end of your blog posts. To set up this feature, log into your WordPress admin and click on your username in the top right-hand corner of the screen (or if you have the bar disabled, you can navigate to Users > Your Profile instead).
Then scroll down to the About Yourself section and add your author bio in the Biographical Info text area. Click save.
The bio you added will now show up automatically on all of your blog posts (along with your WordPress Gravatar that is linked to your user email address) and on the Authors page template.