Measure down from the ceiling on the left side of the window to approximately 1 inch above the window frame, and place a mark on the wall. Duplicate the process on the right side of the window. Place the second mark at the same distance from the ceiling. This ensures that the blind is level with the ceiling and not the window frame. This will give the illusion that the window is straight on the wall even if the window is not.
Place the bottom of the blind's headrail against the marks on the wall, and center the blind over the window. Mark the end of each blind with a pencil. Set the blind off to the side.
Place the end of the mounting brackets against the lines you scribed above the window, and then mark out the mounting holes. Set the mounting brackets off to the side.
Drill holes large enough for drywall anchors, using a power drill and drill bit set. Drive the wall anchors into the holes with a hammer.
Place the mounting brackets against the wall anchors and secure the brackets, using a screwdriver and the supplied screws.
Place the headrail inside the mounting brackets, and then slide the mounting bracket covers into the mounting brackets to secure the headrail in place.