Located scrds.exe through FTP. In that directory there should be a .bat file perhaps named somthing like (start server) That's the file you edit. Not scrds. I recommend you read the link I gave you so you get a better understanding of how it all works. Also I'd read this one too
This is the "new"ish way to create a server.
https://developer.valvesoftware.com/wiki/SteamCMD
Edit - I never use workshop maps so I'm not too sure how to incorporate them into server. Although I'm sure its well documented online.