Is there any easy HTML code for when someone adds my site to their favourites it has its own icon?

is this done in HTML?

if you know what i mean!?

That would be a Favicon. You mean like the blue square with the white "D" on this site?

You can create a Favicon easily but once uploaded it can take your browser, and others, a few days before it appears.

See: http://www.chami.com/html-kit/services/favicon/