about the samplerinfo node - you can create these in the hypershade window. You know how in the hypershade window it shows the general nodes (lambert, phong etc)? if you close that panel up or alternatively just scroll down, you will find a section labelled "general utilities". In that section is the sampler info node -> just middle mouse drag it into the hypershade window and setup the connections (connection editor if you're new to this).

If you haven't got the 2d placement node, you can actually just add the 2D placement node by going into the same "general utilities" section of the hypershade and drag it out. Then u just need to use the connection editor again to hook up the uvfiltersize and uvcoord of the placement node with the same attributes of the ramp. (or if you feel like just redoing your ramp, just delete the ramp and then just click on the ramp button in the hypershade window and it will generate the placement node automatically).