The first step is to remove evrything required to access to air cleaner box. Sometimes you have nothing to remove, in most cases fuel tank and maybe many other things.
Then you open the box by removing the screws. Be careful that they don't fall.
Remove old cleaning element and replace it by new one. Make sure it is correctly set up. On the picture can we clearly see difference beteween old and new one.
Then, you only have to close air box and to reinstall everything you removed on first step.