An effective proposal describes (nb. look up the etymology of this word in the OED) three components of a project:
Area is the subject of your project: representations of marriage, for instance. Range delimits the specific aspect of your subject: favourable portrayals of weddings in television commercials, say. And Structure outlines the manner in which the project will formed.
For the present project, one paragraph of each of the first two components and a page on the third component is a suitable length for the proposal.