There aren't many drivers out there who remember what it was like to hit the road without power steering, but those who do appreciate just how useful this now-ubiquitous invention is. Simply put, power steering makes things so much easier for drivers that it's worth it to ensure this system is working properly.
Like many systems in a vehicle, power steering uses fluid. This makes it easy to keep up with maintenance - you just have to check the fluid and ensure it's filled to the appropriate level. Refilling the fluid is easy and can ultimately save you a lot of money in the long run. The fluid is cheap, but it affects much more expensive parts - so if you take the time to fill it up, you reduce the likelihood that you will need other repairs related to the power steering.
Before you replace the fluid, you have to flush the system. Open up the power steering reservoir and remove the fluid using an eyedropper or turkey baster. Then jack up the car slightly so the front wheels are off the ground and turn the wheels, which will force more fluid into the reservoir.
From there it's the simple process of using the approved power steering fluid from your owner's manual, refilling the reservoir, and letting the car run a bit, adding additional fluid as the reservoir level drops.