Just rename "Main.html" to "index.html" and it should work.
As you mentioned, your server folder is where are the files you want to be accessible on the web should live.
When a web browser gets your server address, that address maps to the server folder (where you put your files).
If there is a file named "index.html" or "default.html" in that folder, the web browser will load that. If not, the web browser will display the contents of server folder.
Or Even you may add "Main.html" as "default documents" and turn of "Directory Browsing" on the web server, if it is administered by you.
I change the Maih.htlm with a index.html. Be carefull to pout a lower case to the i of index.thml. I tryed several time whith a I Cap.
As to the server hosting I didn't find nothing about the "browsing directory".