Do you have to write at the back of a leaflet?

no you don't have to but the back is not the most important bit of the leaflet so don't put really important info on there, you can add info, pictures or contact details are good. Logo's things like that. Make sure the best bits of info are inside and the front looks presentable and makes people want to carry on reading it. If you don't have an interesting cover people wont want to read the rest and will just find a better one.