For a detailed tutorial on how to render using pymol, check this tutorial.

For the full instructions on how to set up python, pymol and the necessary software to process the rendered images into a movie, click here.

Fix from here: for measuring dihedrals, if your pymol fails (esp. Mac) then go here and use that file to replace your PYMOL_HOME/modules/pymol/wizard/ file (open the package contents from the pymol application).