A training center is a venue where you regularly conduct courses. Each organisation may have one or more training centers. If you are doing onsite or 'roaming' training, I suggest to either make a training center per location where you offer training, or create a single location (e.g. at your offices) that you can use as a proxy for other venues.
In the future we will provide a map with pins showing where upcoming training courses will be provided for all Certification organisations.