In the surfaces pane many of the settings have a drop down for adding an image map. 

You are just starting, I don't recommend getting into the shader mixer tab yet. That lets you build shaders with spaghetti strings once you get your head around the concepts, but for Iray, unless you dig up a cool MDL you want to import, you can do everything you need with the settings on the surfaces pane.

So its like the material room in poser? Where I can change transparancy, reflection, refraction etc?

In the Surfaces Pane. This should help.  http://docs.daz3d.com/doku.php/public/software/dazstudio/4/referenceguide/interface/panes/surfaces/shaders/iray_uber_shader/start