The mechanics, in plain language — confirm the specifics yourself before you rely on them.
The direct answer
Kindle Direct Publishing (KDP) is Amazon's self-publishing platform. You create a free account, upload your manuscript and cover, choose which formats to publish (ebook, paperback, and/or hardcover), set your price and royalty option, and publish — with Amazon handling printing, distribution, and payment on your behalf. You remain the account holder and publisher of record throughout.
What stays under your control
Your KDP account, your royalties, your banking and tax information, and the manuscript and cover files themselves are all yours — no service provider, including CDMworld, operates your account or holds your rights on your behalf. Anyone assisting with setup should be guiding you through your own account, not asking to run it for you.
Where the ISBN decision fits in
Print books need an ISBN; ebooks generally don't. KDP offers a free ISBN for paperback and hardcover, or you can buy your own. That choice affects who's listed as your publisher and where else you can distribute the book — see free KDP ISBN vs. your own ISBN for the breakdown.