Un plug the vacuum hose on top of the valve, loosen and remove the big tube nut on the bottom of the valve, I have found if you hit it sharply with a hammer 3 or 4 times before you try to loosen it won't break the valve off, once the tube nut is undone remove the 2 bolts holding the EGR valve to the intake manifold. Remove and discard the gasket and install the new valve in the reverse order. If the tube nut still won't come loose try heating it with a torch, if it's really rusted on you might have to replace the EGR tub along with the valve.
