I want to make and hang a small shelf unit. Any ideas?

Ok so i am making a 2 shelf unit that comprises of a back panel (heart shaped) 2 shelves with 2 side panels. Theres 2 things I would like to know. 1. what is the best way to attach the side panels to the back panel? I plan to atach the shelves to the side panels using those little plastic connector blocks. I'm sure i can get round this one with a little thought but it would be far better to be handed to me on a plate lol. 2. What would be the best way to hang them so that no screws show? It will be made from 12mm mdf and will hold half a dozen of dvd's and half a dozen books and some cuddly toys. Not a great deal of weight but I want to hang it over my daughters bed so i don't want it to have the slightest chance of falling on her. Any help apprecieated. x