Well, in order to become a project management trainer you will need at least one degree/certification in project management regardless of your years of experience (it will give you credibility in front of your students).
So, the first thing that you need to do is get a degree or certification. In my opinion, here are your two options (if you do them both it'll be excellent for your prospects):
- Get the PMP (and if you want to look more professional, get the PMI-SP, and the PMI-RMP)
- Get a Masters in Project Management or an MBA in Project Management from a reputable university.
Now that you have the necessary education to become an instructor, you should start promoting yourself. Start giving free seminars in project management (maybe at your local PMI chapter or at the company you are currently working in). These seminars will attract students, and once you have your first students, you will have more students if you are good (word of mouth marketing).
Alternatively, you can advertise your services online, which is a very cost efficient way to attract new prospective companies.
Other things that you can do to promote yourself:
- Write a book on project management
- Create a blog on project management
- Network with project managers especially in your area through social and professional networking platforms such as Twitter/LinkedIn/Facebook). You have no idea how many companies your professional network will refer to you.