What do you mean exactly? If you're talking about creating an avatar for your username, the simplest way is to use the 'About Me' applet. I do know that the stock Daryna installation disables this. It's easy to re-enable, however if you wish. You will need to install Evolution and evolution-data-server. You will also need to edit /usr/share/desktop/gnome-about-me.desktop and remove the line "NoDisplay=true" (or change to false) if it exists. Once you've done that, simply launch 'About Me' by going to Mintmenu --> All --> About me. Click the generic user icon and select a new one of your choice. That's it. There might be an easier way than this, but I don't what what that might be. Good luck.