I graduated in health service management and now I am working at Univesity as a lecturer. Now, I have a plan to learn a PhD in health service management, health policy, and health economics-related fields. So, how can I get a supervisor?
Most of the Universities abroad has 'How to find a supervisor' site in their website. Most of the searches are also designed to filter the supervisors using key words.
For example in the Researchers/Supervisors site you can search a supervisor with a specific specialty such as Epidemiology or Health service management or Nutrition etc. Then you can view their profiles and make contact based on your enquiry.
You can search for open Ph.D. Projects and apply directly to that specific project. Some Universities provide a fully funded scholarship for their projects. Look over this site: https://www.findaphd.com/
You need to look for the appropriate university, see if that University has a senior lecturer, PhD, Docent specialist on the area of your study, and contact those people, asking if they can supervise you. May be by writing a statement of purpose (a one page description of what you plan to do in your PhD project, or a research proposal). That was how I found my supervisor. Then you can proceed with developing your proposal (Research Plan).