How to create Intranet Project Proposal?

Hi everyone,
I need to create a Portal Intranet site for a company, but I don’t know which be the better way to present a Proposal to my client.
Furthermore I need to know..what are the issues to be considered in order to set a price (hour rate) by issue (Design,Building,etc) or a raw payment for the entire project.
I am thinking use ASP.Net to develop this project.