You need to know what, and how much to buy, so measure the floor area. Multiply length times width, and this will give you the square footage of the floor. Allow ten percent for waste. Buy this much underlayment, and flooring.
Before you begin to install the flooring, you will need to prep the floor. Remove vent covers, carpet, pad, and tack strips. Remove base boards, or shoe molding. Make any necessary sub floor repairs at this time. Sweep the entire floor. If the floor is concrete, you will need to install a moisture barrier. Now you are ready to install the laminate flooring.
Install foam underlayment on entire floor lapping up onto the wall an inch or two. This will be cut off later. Start laying the floor with the tongue cut off running along the longest wall, using spacer blocks to keep the laminate from touching the wall. Cut the first piece of the second row 2/3 of a panel, and the third row 1/3 of a panel. It’s best to run these three rows at the same time to keep the floor running straight. The pieces you cut off of the panels in the first three rows will probably work to start the next rows. Keep in mind that you don’t want the seams to be closer that 12″. If the seams are closer than 12″ then start the fourth row with a full panel. This should keep your seams from getting too close. If the piece you cut off is less than 12″, don’t use it. You may get to a point where you have only two rows going at a time.
Locking panels can be done by inserting tongue into groove at about a 25 degree angle and gently rocking it into place. Using a block, gently tap the panels into each other only until it closes the gap between the two panels. At the end of the row, use a pull bar to tap the panel in place. At the last row, you need to cut the panels to fit, allowing 1/4″ for expansion. You will also need to allow for expansion around any fixed objects.
After the entire floor is covered, you will cut away the excess foam underlayment and install the base boards, or shoe molding. Do not nail into the laminate, nail the trim onto the wall. Reinstall vent covers, etc.