Add new.gif icon after link

You can do that with some CSS. Basically you would add the gif as a CSS background and add right padding to stretch the viewable area to include the gif. You’ll have to adapt this a bit:

.widget_link_list li {
background: url(https://www.saltasullavita.com/baglioni/2014/newBlink5.gif) no-repeat right center;
padding-right: 23px;
}

Good luck