Tape the washers to the heads of the bolts. The tape will be removed after the rod is secure, but it keeps the washers from falling down while you're installing the rod. The washers are necessary, because they distribute the pressure evenly.
Cut the rod with the tube cutter. When deciding how long to cut the rod, remember to leave room for the bolts, nuts and washers at both ends of the tension rod.
Screw the nuts onto the bolt -- as far as they will go without using tools. This way, you won't over-tighten them, and you can easily adjust the tension with your fingers during the next step. Insert the bolts onto each end of the rod, so they look like end caps.
Hold the rod in place where you want it installed. Step up on your step stool or ladder, and unscrew the nut at the end butting up against the ceiling, so it puts just enough pressure against it. Don't put so much pressure against the ceiling that you crack the drywall or plaster.
Step off the stool or ladder and make any adjustments necessary to the rod at the floor end. Loosen the bolt, if necessary, to increase tension in the rod.
Remove the tape from the washers, and touch up any marks you made on the ceiling or floor during installation -- using paint or eraser-type cleaners.