You should have extracted the axleshaft, after doing so, use a seal removal tool to pop out the oil seal from the end of the axle housing. Coat a layer of the multi-purpose grease on the mating surface of the oil seal recess and use hammer and seal installation tools, large socket or pipe to tap the new seal in with the lips in and the metal face visible from the end of the axle housing. If the oil seal is put in the correct manner, the face of the seal should be level with the extremity of the axle housing. Finally, install the axleshaft.