1. Download OOTP5 software (for free) from ootpdevelopments.com or I believe GOM posted a link in one of the threads. Install game.
2. Download league file:
Latest league files. Here is where you are going to save it (follow this file path): C: -> program files -> Out of the Park Developments -> OOTP5 and save it there.
3. Go to that place you just saved the file at (it should save Talksox.lg or something) and double click it, and hit run when prompted. Then when you go into the game itself just go to file open and the league should be there. From there you can call up players, make lineup, pitching changes, etc.