Welcome to OOTP and the forums, bdc.
Having played them both, I can tell you that if you mastered FOF, you will get the hang of OOTPB. OOTPB is somewhat higher on the learning curve than FOF but FOF is no pushover and you have to be really into text sims to enjoy it. So, you will like OOTPB, I think.
To get started, I would recommend going to this web page:
Out of the Park Baseball - Baseball Management Game for PC and Mac
You will see links there for the Tutorials and Manual. The manual is first-rate and up-to-date*. The tutorials are very good but I am hoping that they will be updated and expanded as time goes on.
For modifications (way down the line for you), go to this web site:
Main
Finally, use these forums. Search and search! Everything that you are going to ask has been asked before, I will bet. But that does not mean you cannot ask it again, of course.
(*Unfortunately, the link to it is not working right now. Moderator alert!)