The URL must refer to a report that is in the Report Server catalog database. You cannot refer to documents on disc as reports. Upload the report to the Report Server and then use Report Manager or the reportserver url to browse to the report. From there you will see how a URL is constructed.
http://localhost/reportserver /Report Project1/report1&rs:Command=Render&rs:Format=HTML4.0&rc:Parameters=false&StartDate='01/01/2005'&EndDate='01/01/2007'";