When it comes to finishing Hardwood you may want to leave this to the pros.
It is not an easy task. You can rent the equipment to do the job, however a drum sander. (photo below–is not a pleasant tool to use).
A drum sander is simply a spinning cylinder with sand paper on it, and what makes it tricky is that the drum is mounted on a slight angle. The first pass is diagonal from right to left until the floor is more or less even. You start working from right to left parallel to the floor….and work your way around the room in a clockwise pattern. The tricky bit is in the middle. You never want to start and stop in the same place or you could dig yourself a trench .
These are sheets of sandpaper that fit the drum sander–each machine is different so buy your paper where you rent or buy the machine. On harder species of wood we will start out using 18 grit, then 24, then 40, then 60 or 80.
The machine blow is called an edger. This has a spinning disc and casters or wheels at the back. It tilts forward and is used for sanding close to corners and walls. IN the same way you use coarse paper and work down to smoother finish as you work.
These are the discs used in the edger. Edgers will usually have a light that casts down on the work surface… this one was broken!