As with anything, the more you use it the better you get and more familiar you will get with the platform. Take small steps at a time, start with posting a story or blog by clicking the submit a story link at the top right of this page. Once your very familiar with that then try commenting on things. I see that you have posted a blog with this post already but learn how to edit it in the markdown box to add some visual style to it.

Don't overwhelm yourself by trying to figure out what a minnow, dolphin and whale is at the moment. This will all come in time.