Blinn is a type of specular setting. There's quite a bit of information on it to be had on the net. While not Daz or Poser specific, the information would still be helpful I'm sure.

 That said, if you're looking to use Blinn in Poser, just go to the Advanced Material room, right click in an empty space in the material section and choose New Node>Lighting>Specular>Blinn

Playing with the node is probably the best way to figure out how it works.