How do you lay floor boards onto concrete floor?

Is this sub grade? If so-

First you need to apply a vapor barrier. A good 4 mil plastic. Tape the seams very well and run it up any supports and walls about a 6 in. Tape this up well also.

Buy all the material bellow, open the flooring and let the plywood and flooring sit in the area it will be going for 3 to 4 days. This it to acclimate the wood to the moister where it will be going.

Then lay down 3/4 in or 5/8 in plywood over the entire floor. This should be exposure rated but NOT pressure treated!! Leave a healthy 1/4 gap between every sheet and 1/2 around any non moving structure (wall, support). This is for expansion.

Now apply a low VOC glue to 1/2 in plywood and lay it down, oriented in the opposite to the first layer. This orientation will give you better coverage and strength. Putting the 3/4 down first is key because now you are going to take a brad nailer and nail all the sheets together as well. The glue and nails, along with the counter oriented plywood will give you a solid sub surface. Be sure your nails will not penetrate the bottom piece and compromise the vapor barrier. Leave 1/4 and 1/2 gaps as above.

Now apply your engineered wood floor. Stick with engineered wood. Even though you have done everything you can for moister, there is still more around than you think. A good engineered floor with a thick top coat of the finish wood will look great. Engineered floor is the way of the future. It's uses less of the wood we want to see, and is more stable.