I actually wrote this for you in the other thread you asked this question.
As much as I would like to help you, what you need is a daunting task. I could literally write for days and pages upon pages of info and still not cover everything you are asking to know. There are a couple of nice deep threads around if you search about managing bullpens and game-play stuff.
What I would recommend is to start watching all of the Baseball you can. Pick a high budget team to start, that way you don't have to worry as much about development right away. Maybe the Dodgers or Nationals if you are a National league guy or the Red Sox or Tigers if you like the American league.
Just start playing. Play exhibition games, start a franchise and play all of the Spring Training Games. Take small steps to manage your team. Don't make any changes right away. Baseball is a game of trends so the players that suck or are struggling today could be your next break out player that gives you the push to the Playoffs.
Read as much as you can, watch as much as you can. Baseball is a huge sport. Both in History and Scope. It can be boring in its minutia and then become the most intense and exciting moment of you life the next second, literally. I seem to stand alone in my opinion, except for a few old timers, in that I feel MLB The Show 14 is an amazing portrayal of the sport I love.
Welcome to your new obsession. If you have specific questions feel free to shoot me a pm I would be glad to help.
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