Once you are in there you will see you can setup the parks
If you are playing historic you will need to go in and actually setup each park, if they are no longer in use. I am playing the 80 Twins. I had to go to the
https://forums.ootpdevelopments.com/...d.php?t=287547 thread by Silvam14 and find the Metrodome that he recreated. Find your team, find the historic park, save it under BALLPARKS in your OOTP settings which you will find under documents> out of the park developments > OOTP Baseball 21 > ballparks
Yes, the file MUST be in there.
He has the Day and Night pictures, the diagram, and the Obj files all in there.
Once your park is loaded click on ACTIONS in the right hand part of the page, click on manually import data from file into this park and click on the .prk file that he has placed in the directory of the park.
This should get you, I think, where you want to go?