You can find all settings in the Paymentech Orbital chapter of the dotnetcharge manual. All not required fields can be blank e.g. the Hash/Certificate field. The error is caused by missing or wrong installation steps. You must add some lines of code for the dotnetcharge provider and sometimes it is also required to rebuild the provider with your dotnetcharge.dll. Please find all information in the following chapters:
Test the .netCHARGE credit card interface