Building a Sitemap from files and folders

Hello all I am new here so I am sorry if I miss something.

I am looking to find out what would be the best way to build a Sitemap from the folders,subfolders, and files that are in my website. I have a document folder that has a series of subdirectories and pdf files. Each subfolder has a corresponding aspx page in a different folder.
I am hoping to find a way to dynamically build a sitemap from these folders and files. Any ideas or suggestions would be extremely helpful to me. Thanks for reading...

p.s. I use c#