The official Medicare website has a feature called the Medicare Personal Plan Finder that can direct you to Medicare Part C plans available where you live. It also gives information about each plan's general terms.
But to know exactly what a plan offers and what all its costs and restrictions are, you have to contact the issuing insurance company itself and carefully read its written materials. You can get help deciphering plan materials by contacting your [local State Health Insurance Assistance Program (SHIP) or Health Insurance Counseling and Advocacy Program (HICAP), which provide free expert assistance.
It will take me several reads to get through all this info, but it's very helpful in sorting out fact from the fiction pushed at us by health insurance companies.