For formal training, start with
Education Services - Progress. There are several different options there, including online training, instructor-led training, and customized training solutions.
If you have the opportunity, join a Progress User Group or attend a conference. Conferences are a tremendous training value. I have been lucky enough to attend several Progress conferences and the knowledge I have gained from them has significantly accelerated my career progression. Conferences and user groups are also great ways to expand your network of business contacts.
Review the material available for download from previous conferences. Look at:
pugchallenge.org (North American PUG conference)
pugchallenge.eu (European PUG conference)
Exchange (Progress' own conferences)
There is a wealth of in-depth information available at conferences, and much of it is not available anywhere else. At those links you will find slide decks, audio recordings, videos, and even a bit of sample code. Good luck.
In case you haven't found it yet, look at the
Progress Knowledge Base. It contains information from past Progress Technical Support cases and contains a lot of in-depth information about the products that is not in the documentation. Its contents are also available in a downloadable Windows application called
ProKB that allows for flexible offline searches of Knowledge Base content.
You have already registered with this forum, that's a good start. Welcome! If you ask questions here and demonstrate a willingness to learn and to diligently answer the follow-up questions asked by other users in their efforts to help you, then I am sure that many people will be willing to continue helping you. You should gain a lot of value from participating here; I know I have. All it costs is your time. As you gain knowledge, you may eventually start helping other people here with their questions. Giving help can be just as educational as receiving it.