GEtting plugins and google analytics on my blog

Hey guys

So – i have a blog that’s on wordpress.com. I’m trying to get Google analytics, and have learnt that you need a plugin for this. However, there is no plugin section on my dashboard.

Firstly, whats the difference between wordpress.com and wordpress,org – why have i had to register with www.ads-software.com?

Secondly, what action must i take now to set my blog up with plugins and then google analytics?

Thanks,