Curtains block out as much light as possible and provide privacy when you properly fit the curtain pole. Mounting it past the width of the window allows some overlap for the curtain. Most window frames have a header board behind the wall that provides a solid foundation for the brackets when you fit the pole properly. Choose a pole that will handle the weight of the curtain and accommodate the hooks you use to hang it.
Measure 15 cm (6 inches) from the top right corner of the window frame and mark it. Measure from your mark out to the right an additional 6 inches, and mark it. This is where the top of the curtain rod bracket will mount. Go to the top left corner and measure 15 cm (6 inches) up and 15 cm (6 inches) to the left, and make the mounting mark for the left end bracket.
Place the end of the tape measure inside the upper left corner of the window frame, and measure to the right inside corner. Divide the measurement by two to determine the centre of the window. Measure from the inside top left corner to the centre measurement, and make a light mark at the top of the window frame. Measure from the top centre of the window up15 cm (6 inches), and mark it. The top of the centre curtain rod bracket mounts at the mark.
Position the top of the end brackets at the measurement marks on both sides of the window. Mark the mounting hole locations on the wall. Place the top of the centre bracket at the centre mark on the wall, and mark the mounting hole location.
Drill pilot holes at the mounting hole locations with a smaller diameter bit than your mounting screws. Place the brackets on the wall and secure them with wood screws and a Phillips-head screwdriver.
Set the curtain rod into the hooks of the brackets. Place a level on top of the curtain rod to ensure the rod is straight across the window. If necessary, loosen an end bracket and slide the bracket up or down. Tighten the mounting screws to secure the bracket. Take down the curtain rod and install the curtain on the rod.
Install the curtain rod back into the brackets. Tighten the rod securing screws at the front of the brackets if your brackets use them.
If mounting to a hollow wall, use toggle bolts to secure the brackets to the wall. Instead of drilling pilot holes, drill holes large enough to fit the toggles through the wall.