I just lifted my carpet, what's the next step to make the floor look nice? How do I fix nail holes?

I assume you have hardwood floors under the carpet? You will probably want to refinish the hardwood unless you like the rustic look.





If you don't want to refinish you can look for a filler that matches the existing finish and fill the nail holes.





If you decide to refinish first fill all the nail holes then sand the floor.





After sanding you thoroughly clean all the dust up then wipe the entire floor with a rag dampened with mineral spirits.





After the solvent dries you stain the floor following the directions of the stain manufacturer. After the stain dries you can apply either a waterborne polyurethane or oil based polyurethane top coat.





You will probably want at least 3 coats. Though follow the manufacturer directions for the product you use.