If you've got a concrete floor and you want the warmth and livability of hardwood instead, you can't nail down a timber floor as you could if the surface was wood. However, you can still get that wood floor that you want. Glueless or "floating'' timber floors are designed to snap together like puzzle pieces without being glued, nailed or otherwise attached to the subfloor. Start with a clean, solid concrete base.
Take off the trim from the base of the walls around the edges of the floor, using a pry bar and hammer. Don't break the trim. Set it aside.
Cover the floor with rows of plastic moisture barrier, laying them out side by side and cutting them at the ends with a razor knife.
Lay one no-glue timber floorboard along the edge of the floor, putting plastic shims between the board and the wall. Snap a second board onto the end of the first one, along the edge, again setting shims there.
Lay the rest of the first course in the same manner, connecting the boards end to end. Cut the last board on a mitre saw to fit.
Lay the next courses of boards off the first one, linking them along their long edges. Stagger the positions of the boards between courses to give them a random look. Cut the ends as needed. Work your way across the whole floor.
Use a table saw to length-cut the last course of boards to fit along the last edge, with a 3/8-inch space there.
Put the floor trim back in, using a trim nailer. The will hide the gaps around the perimeter.