Service Endpoint

HTTP web service methods deployed on a Salesforce org follows a pattern. It starts with the instance URL followed by the resource location. The format goes as

https://\{instance}. salesforce.com/services/apexrest/cg/SDrive/{resourcelocation}

The instance is a variable unique for each org, it is the characters between "https://" and "Salesforce.com" in your org URL. The resource location variable for S-Drive files is "files".