Basically, apply the DE carefully, since the dust is not good for you in large quantities. Let it sit in the carpet for two or three days then vacuum up. It's hard on the vacuum cleaner, so don't overdo.
Put some on the spines of your animals and rub down to the skin. Avoid the eyes and be gentle with the ears.
The stuff is drying; that's partly how it kills bugs. It may be hard on your hands and you may want to pick up a dust mask for application. Repeat every time you vacuum because you have to catch the egg hatch.
Keep your pets out until you have finished spreading the stuff around. It is only the food grade you should use and everyone is different so watch your pets' paws.
Note: Human consumption of this product and in your pets' food is OK and many say good for you. But do your own research and make up your own mind.