What is a one-sentence summary of the following article?
Most likely, you will need to unscrew the legs from the dryer so it can be safely stacked. The manufacturer may also ask you to place adhesive foam backing on top of the washer to cushion the dryer and reduce vibrations. If so, this should be included with the stacking kit.   Keep the legs in a safe place in case you decide to unstack your appliances later. Position the washer at least a few inches away from the wall. You'll need enough space to be able to attach everything, but you don't want the appliances so far away from the wall that it's hard to slide them back into place when you're done. At least two people will need to work together to lift the dryer up. Squat bent at the knees, and place your hands underneath the dryer. Lift carefully, using your legs rather than your back to pull the weight. Place the dryer on top of the washer.  Dryers are heavy. Lifting one improperly can cause injury. Lift carefully and ask for more help if you need it. Your stacking kit should include an attachment or bracket that will join the washer and dryer together. Most of the time, this is placed on the back of the appliances. Attach it according to the manufacturer’s instructions. Most likely, the attachment or bracket will be held in place with bolts, so you’ll probably need an adjustable wrench for this. Once your stacked washer and dryer are bolted together, attach the water hoses to the washer and the gas line (if applicable) and air vent to the dryer, according to the manufacturer’s instructions. Make sure they are secured properly to prevent leaks.  Do this just after you attach the washer and dryer with the bracket. Since the appliances will be pushed away from the wall to attach the bracket, you can easily reach the connections. Washers will have a water supply hose and a drain hose. Attach both of these. Dryers will have a vent duct that needs to be attached to a vent going outside. If you have a gas dryer, you will also need to attach the gas line. After connecting the hoses, vent duct, and gas lines, plug in the electrical cords for both the washer and dryer. Now that everything is connected, you can carefully push the washer and dryer into position near the wall. Remember to leave 2 inches (51 mm) to 3 inches (76 mm) of clearance! Run an empty washer through a regular cycle. Then, turn the empty dryer on and let it run for a while. Pay attention while the appliances are running. Some vibration is expected, but you want to make sure that neither rocks or sways. If they do, it may be a sign that your washer is not level.

Summary:
Follow the manufacturer's instructions for prepping the appliances. Carefully lift the dryer up, with help. Secure the appliances to each other. Attach any water, gas, and vent lines. Plug in the appliances and slide them into place. Try a test load.