Before I show you how to create a Gravatar I'd better explain what one is and why you need one!
Scroll to the bottom of the page and look at the comments. Do you see my image against the first one?
Good, that's a Gravatar.
For those of you too bone idle to scroll down, this is what you would see:
Especially relevant for those of you who write "guest" blog posts, you'll want readers on those other sites to see you, rather than one of these less than flattering images that appear (depending on the site settings) if you haven't created a Gravatar.
There are sites all over the internet riddled with Mystery Persons - please don't be one of them!
A Gravatar is associated with an email address or addresses BUT only if you set it up correctly.
If you run a WordPress site and want to ensure Gravatars show up, if you insist, you could try looking at the WordPress Codex and following their instructions, but for most WordPress users it will be far easier to use a theme that does most of the work for you.
You know how much I love Thrive Themes - Gravatars are shown by default - no messing about with code
UPDATE - I'm now using Thrive Comments on the site and although everything above still applies regarding How To Create A Gravatar - the look of the comments is different from the screenshot above