Bokeh in a photograph is determined by the lens and aperature settings used to create the photograph. To achieve bokeh, you need a fast lens with at least an aperature of f2.8, f2, f1.8, f1.2. Prime lenses work great for bokeh. Shoot in Manual or Aperature Priority, wide open – meaning at your largest f stop (which is the smallest number)
If you do not have a lens with a large aperature as described above, you can also achieve bokeh by increasing the distance between the background and your subject, and increase the distance between your subject and the camera. To achieve highlights hitting the background, shoot with backlighting, or sidelighting.
Bokeh – Wikipedia In photography, bokeh (originally /ˈboʊkɛ/, /ˈboʊkeɪ/ BOH-kay — also sometimes pronounced as /ˈboʊkə/ BOH-kə, Japanese: [boke]) is the aesthetic quality of the blur produced in the out-of-focus parts of an image produced by a lens. Bokeh has been defined as “the way the lens renders out-of-focus points of light”.