Add power steering fluid if the level is low. Check the owner's or service manual for the type of fluid before adding anything.
Find the bleed valve and apply some penetrating oil. Push a length of clear vinyl tubing on the end of the bleed valve. Tubing length is better too long than too short. Raising the wheels above the ground with a jack and jack stands can make turning the steering wheel easier.
Run the tubing into a dedicated catch container to bleed the system of both air and old fluid. Be careful not to run the system out of fluid! Start the engine. Crack open the bleed valve slightly. Turn the steering wheel several times lock to lock. Close the bleed valve. Add fluid. Repeat until the fluid runs air free.
If the fluid is known to be new and free from crud, then running the return line back into the fluid reservoir is an option that does away with the danger of running the system dry. Fasten the end of the tubing to the reservoir with a rubber band or bailing wire. Start the engine. Crack open the bleed valve slightly. Turn the steering wheel several times lock to lock. Top off the power steering fluid once the air is no longer in there. Turn the steering wheel a few more times and check the fluid level once more before driving.
At least in theory it should be about this easy!