How to change my avatar?

I looked everywhere and I couldn't get an answer. I own a blog and I would like to change my avatar for it. (I do not want those ugly one offered on the website.) I can't find a section to customize my avatar is is normal. I know wordpress has gravatar... but I made my blog with only altervista. What can I do?

Gravatar is "Globally Recognized Avatars", so you can use it even if you aren't on wordpress.com. If you use your admin email, your blog will recognize your Gravatar.