If you are an OCP, then there is only one exam required to become an OCM. It is a two-day hands-on exam that is given only a few times a year in any given country. The link to the schedule is below. In addition to the test requirement, you must complete two advanced hands-on courses (eligible courses in link below):
The two steps then are take the courses (submitting the courses to Oracle Education as part of this step) and then take (and pass) the test. You can so these in either order.
Eligible advanced courses (scroll down to "These Advanced or Specialty courses meet the Hands On Course Requirements for either OCP or OCM-Level certifications.")
OCM 11G Schedule
OCM exam link: