Overwrite "Created By" & "Modified By" field

Question

We have created a interface in website to upload the document via Sharepoint Copy service.
We are facing issue for "Created By" & "Modified By" fields of sharepoint. When any user upload document we need to pass their website user name for Created By" & "Modified By" but right now its always taking
sharepoint authenticated user name.
So, our sharepoint service is configured with windows Admin login to access sharepoint, so all the document is uploaded as Administrator user instead of website username of the user.
Please suggest me if we have any oition to overwrite these two fields.

Answer 1

Please see my code for copy document and the field "ows_Author" is always saved as windows logged-in user.
  SharepointCopy.Copy copy = new SharepointCopy.Copy();
 SharepointCopy.CopyResult cResult1 = new SharepointCopy.CopyResult();
            SharepointCopy.CopyResult cResult2 = new SharepointCopy.CopyResult();
            SharepointCopy.CopyResult[] cResultArray = { cResult1, cResult2 };
            SharepointCopy.FieldInformation fieldInfo1 = new SharepointCopy.FieldInformation();
            SharepointCopy.FieldInformation fieldInfo2 = new SharepointCopy.FieldInformation();
            SharepointCopy.FieldInformation[] fieldInfoArray = { fieldInfo1, fieldInfo2 };
 fieldInfo1.InternalName = "ows_Author";
                    fieldInfo1.DisplayName = "Created By";
                    fieldInfo1.Type = SharepointCopy.FieldType.Text;
                    fieldInfo1.Value = "1;#" + Uploaded_By;
                    fieldInfo2.InternalName = "ows_Author";
                    fieldInfo2.Type = SharepointCopy.FieldType.Text;
                    fieldInfo2.Value = "1;#" + Uploaded_By;
                    SharepointCopy.FieldInformation[] fieldInfoArray1 = { fieldInfo1, fieldInfo2 };
                    uint copyResult = copy.CopyIntoItems(fileName, destinationUrl, fieldInfoArray1, fileContents, out cResultArray);