Simple Cooldowns is intended to be just that, simple. No bells or whistles or hours of set up and customization. Just make a panel, drag stuff into it, move it, size it and job done.
That said there are some options available. Panels are like action bars but without protected doo-dads and what nots, each panel contains sockets (like action bar buttons) and the socket contains your chosen item or spell. Panels can be adjusted for size (this happens via socket sizing), postion and orientation and will by default have there visibility attached to the spec active at the time they were created (a setting will be added to change this). Sockets can have there size and visibility changed and they also have 'overlays', these are coloured textures that can be used for range checks and usable checks.