Measure the total area of the wall you want to cover. If you only want to cover a portion of the wall, measure that area instead. This will give you the dimensions you will need for the curtains and the curtain rod. The rod will need to be equal to the width of the area you are covering and the curtains will need to be equal to the height of the wall and about one-and-a-half times the area you want to cover.
Inspect the hardware included with your curtain rods to see how many screws are needed to install the rod supports -- this will tell you how many marks you need to make. Mark the wall where you intend to install the curtain rod. Hold a carpenter's level against the wall to ensure your markings are even.
Hold the curtain rod supports over the markings and use a drill or screwdriver to install screws and secure the supports to the wall. As you install each screw, do not tighten them all the way -- the supports may slide around as you work, so it is best to wait until each screw is partially screwed into the wall before you tighten them the rest of the way.
Slide the curtains onto the rod. You may need to iron the curtains before hanging them if they are very wrinkled from being folded in the packaging. If the wrinkles are minor, they will smooth themselves out after hanging on the rods for a few hours.
Hang the rods on the rod supports. Some curtain rods will have an additional screw you can install to keep the rod from moving around on the support -- check the packaging for detailed instructions. Adjust the curtains so they are centered on the rod.