Rather than lecture or force you to read about what game design is all about, nothing beats playing a game to teach you about it!
1) Go to http://gamestarmechanic.com (integrated below!), then sign up and play, preferrably to completion.
Hide/show GameStar site
2) Write a blog post highlighting what you've learned and what you liked and disliked about the experience.
3) Post a link to your blog post here for credit!
4) Add "Played GameStar Mechanic" and a link to your blog post to your Missions completed!