Cannot upload (put) new file using API explorer

I am trying to use the api to create a new document in projectwise explorer. I keep getting a 403 forbidden error 

{
"errorId": null,
"errorMessage": "The specified origin is not allowed.",
"errorDescription": null
}

Is this something I should be able to do with the api? 

I have changed the web.config file to allow Cross Domain requests. <add name="Access-Control-Allow-Origin" value="*" />

Thanks

Byron