I wouldn't recommend installing wood flooring over concrete but there are ways to do it. One method is to install pressure treated runners directly to the slab at 12 or 16 inch centers. A 6 mil vapor barrier is then installed over the runners with a 12 inch lap. You can install the flooring directly to the runners but a layer of 5/8 to 3/4 inch plywood is preferable to avoid potential sagging. The runners can be attached to the the slab with tap con screws (preferred method) or nailed.
The second method involves leveling low spots with sand, installing 6 mil vapor barrier lapped 12 inches embedded in tar at the lower lap and taped at the upper. Two layers of 3/4 inch plywood are then installed directly to the slab. The first layer is screwed or nailed to the slab in the traditional manner. The second layer is installed either perpendicular to or at a 45 degree angle over the first. The second layer floats over the first to allow for movement between the layers. Which ever method is utilized the wood floor is installed per manufacture instructions with cleats or staples.
There is engineered flooring produced for use over concrete and your flooring supplier should be able to provide options for you. Cork (flooring not rolls) is also a great option and again your flooring supplier should be able to provide options. My recommendation for concrete floors is to install tile. There are many tiles on the market that mimic the look of hardwood. Cost and installation is both less and easier than wood for this application and you don't have to worry about water or moisture damage to the flooring. Below are some examples of tile.