help with Benjamin and Medwin stovetop machine

Hi Everybody, I just purchased from our as is thrift store a Benjamin Medwin stove top espresso machine, apart from the name on the handle, no other model # so I'm not sure what model it is. It is stainless steel construction with screw on black top piece. I've wanted one of these for a while but now I have it I am completely clueless as to how to use it. Any help or ideas would be much appreciated. Thanks, Fran