It is a process, these sites will help!
Ask your vet for Comfortis or something similar to treat the pets. Then use flea bombs in the house. Make sure the pets are treated just before you bomb so they don't bring fleas back in.
We treat our cats with Vectra that we get from the vet, each month, all year long to avoid the flea situation. But 2 years ago we had them. My husband didn't want to use flea bombs so we used a combination of baking soda and salt. I did about half and half. Then I sprinkled this all over my carpet, let it sit for an hour then vacuumed it up. The more you do this, the better it will get. I did it a couple of times per week to start then once per week. There are also some videos on You Tube that may help. Good luck.
Vet told me to use borax, so I got 20 Mule Team Laundry borax, put it in a glass jar and poked lots of holes in the lid, sprinkle all over affected areas - rugs, furniture and beds. Leave for 3 hours and then vacuum up. It won't hurt pets or you.
Then I use Greenerways Bug Repellent that is non-toxic on me. Its lemongrass oil, citronella oil and cedar oil that I get on Amazon.
Then I read up tricks on the internet, and it was recommended to use towels for the cats to lay on.... shake out daily, wash weekly.
Fleas hatch every 9 days, so repeat after the first treatment 9 days later.
Borax helped and these are all included animals butt no luck with the cat......