How do I put a picture/photo in my Mylot avatar?

As you said Bontheka, it is very very simple.. Go to the " Edit my Preferences " in the right side of our site, which is green in colour. When you are there you can upload your picture or any other from your computer. Submit / update the picture. You can edit your details also there as and when you like it. All our preferences get edited there only, like your password etc.