"google analytics for wordpress" plugin help

Please excuse my newbiness and overall lack of knowledge, however I’ve managed to install the plug in “google analytics for wordpress,” and as far as I can tell, I can see my numbers (although they don’t match the total site numbers) and I’m the only one signed up right now. But I want to add other authors and I don’t know how. I suspect it’s really easy…but not if you don’t know how.

Also, as I’m tracking two other sites on Google Analytics, how can I keep the other authors from seeing those numbers?

I hope someone can help me. I’d like to be able to get my site up and running with additional authors: https://www.carbuzzard.com