You will need:
-length of 1/16 in (or other) the width of the window to where you want the curtains to stop plus about 4-5 inches
-eyelet screws, 3 per window
-cable crimps or ends
-needle nose plyers
-some curtains to hang
-tape measure helps.
Step 1: Measure the Window You Will Be Covering.
Add about 4 inches to this number for the loops at the end.
You will want to only loop and crimp one end of the cable to start. We will check the final length before looping and crimping (swaging) the other end, this will ensure we get the cable pretty taught and without too much sag.
Here my window is just over 39 inches, I cut 45 inches of cable to be safe.
Step 2: Install Eyelets Above Window.
I used the molding as it was more secure than the drywall, make sure you use a strong enough eyelet and anchor it well enough to support the weight of the curtains and the force of opening and closing them.
I used closed eyelet screws that I opened just a bit with needle nose pliers to fit the cable. This way I can re-close them after I hang the curtains and know the cable wont come off or fall down.
Place one eyelet on each side of the window, and one in the middle for support.
Step 3: Close (crimp/swage) the Ends of the Cable.
Do one end first, then check the length and find out exactly where to place the second end to get the cable as taut as possible.
Thread the cable through the end, then loop it back around, make a loop about .5-1 in in diameter.
Using a hammer, crimp the cable end around the base of the loop, and check it to make sure it is set well.
Check cable length with the end already threaded on the second side. Create the loop, pull cable tight and either mark the crimp location or hold it in place.
Hammer the second crimp on.
Once the second crimp is installed, trim any extra cable.
Step 4: Install Curtains
Thread the cable through the curtains and hang the cable on the eyelets. Place the middle eyelet in between the two curtains.
Close all the eyelet screws back up if you want for security, and you are good to go.