Get racks and measure
The first thing you need to do is to head out to the store and then look for the racks that you want to install in your bathroom.
Now you are going to have a lot of options over the racks, so you can go on and spend as much time as you want trying to find the racks that are best suited for you and your bathroom.
Or you can feel adventurous and get some rather odd looking racks.
After you have the racks, measure their dimensions so that you know what to do next.
Now after you have measured the size of the racks, you need to drill holes in the bathroom walls accordingly, based on just where it is that you want to install your racks. Make sure that the markings are precise or you will have to repeat this step a few times.
Also try and get some reinforced nails, so that they can easily support the weight of the rack and avoid it causing many problems.
Install and use
After all of that is done, what you need to do is to go on and install the racks into place. Hold the racks in place and then pass the nails/screws through the holes that are located on the racks.
This will get the racks ready to be used and will make sure that your towels have a place to call home.
Once you are done screwing the racks in, just make sure it is firm and secured in place.