You can't just run any old executable file as a service directly. They have to be written to work that way. If you want to run something else as a service, there's an old tool called SrvAny.exe that can help with that.
As Dave mentioned SrvAny is very old and I believe only available in equally old Windows resource kits which are difficult to get these days. You can download and use a tool which provides the same functionality but it is still under active development call NSSM – the Non-Sucking Service Manager.