A shortcode looks something like this, and can be used in the WordPress post editor:
[shortcode] Content that goes inside it! [/shortcode]
They basically act as HTML (with an opening and closing tag), but in a lot simpler form. Shortcodes generally remove the need for you to memorize any HTML.
Here are all the shortcodes in Chronicl, and how to use them:
Note Box ↩
Description: Allows you to create a gray box for any notes you need in posts.
[note] ...content here... [/note]
Alert Box ↩
Description: Allows you to create a dark box for any alerts you need in posts.
[alert] ...content here... [/alert]
Drop Cap ↩
Description: Allows you to create a drop cap for typographical awesome-ness.
[drop]C[/drop]hances are, you're using a drop cap...
About Widget Custom Link ↩
See this tutorial for instructions on how to use this shortcode.