ENvironment Map Help needed

alright, how do you alter HDRIs for backgrounds? i got a free one, i’m having nothing but trouble trying to dfollow tutes as what i get just doesn’t match what i’m reading/watching.
here’s a cut down, basically my World setup and a test plane/box, and the preview version of the image as the actual images are 3k and 8k.


https://dl.dropboxusercontent.com/s/0osdqlfk4lesn87/MonValley_G_DirtRoad_preview.jpg?dl=0
i’ve been trying to move and scale the image to fit appropriately in my camera, and the bugger just will not move sensibly as it does, eg, in this tute: https://www.youtube.com/watch?v=EHnMRDvQeEg [at about 16min in]
also, this said to set the HDR to “sample as lamp” to cut noise but i’ll be buggered if i can find where that setting is?
TIA

It’s been renamed to multiple importance sampling, found in the material’s Settings panel.

Edit: Here is the wiki page on MIS.

As to the mapping - http://www.pasteall.org/pic/show.php?id=104083