Visit the dentist. First, you need to visit a dentist and have them do a thorough examination, including x-rays to determine your overall dental health. Then they will have a long discussion with you about the advisability of such treatment, what to expect, etc. This is not to be taken lightly, as many people with false teeth are not happy with them.
Get a consult. You first have to visit a dentist. They will need to review your medical history, medications, allergies, etc. At that point, some impressions may be taken as well. If you have horribly broken down and infected teeth, the doctor may suggest having your teeth cleaned to remove as much bacteria as possible before extractions. You may then be referred to an oral surgeon for the extractions.
Visit your dds. If you really want to extract all teeth and wants dentures your answer is right there in your question.
Visit a dentist. I would seek your personal dentist for help. If you do not have one i would seek a dentist with nice online reviews concerning false teeth, dentures, partial dentures, and perhaps implants. You can also ask friends with false teeth about their experiences.
See a prosthodontist. Your prosthodontist is well trained to guide you through this treatment. You may choose 'immediate denture" treatment, in which you will never be without teeth. You may choose to have "teeth-in-a-day" or an "all-on-4" procedure which provides fixed teeth that same day. Check them out and see your prosthodontist.