Whats The Dirt on Stoichiometers

I havent had my A/F gauge for that long and to tell you the truth, my auto skills are having a hard time reading it. What essentialy should it be doing?

When i'm in idle, she's at the last lean (red) bar....when i cruise, she's bouncing back and forth ( which i know is normal, and also very fun to watch ) and at WOT, she hits the last rich (green) bar quickly, and then back to bouncing...

thanks