[Plugin: Gallery Widget] Adding Sub galleries

How to I add sub-galleries? I would like to create a gallery for our festivals and have each year in it’s own gallery. I already have other galleries and don’t want to make a separate gallery for each festival year. I would rather make a main festtival gallery page that will then open to give each year separately. How do I do this?

http://wordpress.org/extend/plugins/gallery-widget/