This video shows step-by-step procedures for installing weather stripping around an outside door.
Ikea shelf: https://amzn.to/2dXkhXc
Wall mounting is a bit tricky. In this video I have the shelf resting on the baseboard. To mount it high on the wall like you see in the IKEA store requires that you secure it to the studs. In most homes built in the United States there are what they call ‘studs’ behind the drywall. The wood studs are 1.5″ wide and are spaced 16″ apart [at least they should be]. To mount this high on a wall you will need to secure the 2 provided brackets into the studs with wood screws that are not provided. Then I would buy 2 more brackets and install 2 more brackets for a total of 4 per unit. Then once it is installed, don’t put anything too heavy or valuable on the shelf until you feel comfortable that it won’t rip off the wall.