how to create a RESTful service out of my existing c# app

I see your project now.

 

and it's basic code with everything in 1 project.

 

what you need to do is separate out the logic into 3 tier architecture pattern i.e. backend, business layer and front end.

 

take out all code dealing with db like edmx etc into a new class library project, 

create another project for service layer which calls this data project and use it in windows app project.

create new web app project, and refer that service layer into web project. you will need to host this project in IIS server somewhere.

 

if you dont know ASP.net then you have to learn, there is no option

Your zip file contains only the solution file, nothing else, you should zip the whole solution folder to include code.