Try this, add a new layer. open the layer palette ( a tiny window) there is a little F , this drop down menu should reveal "pattern overlay". a window should pop up and in this window you can scale available patterns - if you don't have a chevron pattern you should define one. The chevron becomes one pattern in a collection of swatches. i would recommend saving the "preset" patterns, otherwise the addition is temporary. also if this scale % is not accurate enough. note this - in the pattern drop down menu - hover over the tiny preview of the repeating pattern it's pixel dimensions should be displayed. simply make a new document with these dimensions, fill it with the desired pattern , scale the entire document to size, to a pixel dimension and _define this_ as a new pattern.