Hey Sue – Welcome!
To change your Avatar, click the "My Profile" link at the bottom of any page. From there, you can upload an Avatar from your computer.
As for RSS, I'll try not to get technical about it – but it's a way to be notified whenever new articles are posted to this site. With so much Spam, most people ignore emails – even if they get pass the SPAM blockers. RSS allows reader to stay up-to-date (called Subscribing) without providing any information to the website the content comes from.
To Subscribe to my RSS feed, locate the RSS logo in your browser window (different browsers put the logo in different places – but usually in the Address Bar). Clicking it give you several options of which programs you want use to read the feed, e.g., Google Reader, Outlook, Firefox, etc. Once you make a selection, you are done.
You can read about teh gory details here – http://en.wikipedia.org/wiki/RSS