[Dancake]

Pretty much as Clan has described. Make sure the surfaces on the block are clean before fitting the plug. Scotchbrite is great for cleaning up the surfaces. I normally use a long impact socket that fits inside the hollow of the plug. This allows you to hold the plug in place with enough length in the socket to safely strike it with a hammer. Try to keep the plug square when striking the socket.

Core plugs are an interference fit, so if both surfaces are clean and free from pitting, it should form a permanent seal once tapped into place. No need for sealant. You can in some cases go too deep with a core plug, so check the thickness of the material to see how deep you can afford to go with the plug. You ideally want to seat the core plug just beyond flush, ensuring that the full circumference of the plug is in even contact with the hole into which it is being fitted.