This is mostly for the newbies. We will be going into Spring Training after the Rule V draft and it is time to start nailing down the roster. To add to the roster, select Spring Training Squads under the Managers Office-Player Settings. Go through each level and invite players that have a ML future for the most part, both position players and pitchers.
Things you may want to know about is the Rule V draft. Players that have a 5 in the red diamond are exposed to the draft. Make sure players that have ML potential are on the 40-man roster to protect them. To view and make changes is done through the GM's Office-Roster Management-Edit Rosters.
Setting the lineups is done through the Manages-Office Lineup. However setting Rest, Pinch Hitting and Defensive Replacements is done under Manager Settings. Also here are Manager Settings, you might want to play with those settings and read about what they do during Spring Training.
Pitching is setup just like the lineups. However, there is this thing called Player Settings that is relatively important during Spring training for pitchers. Since you don't want them to go 9 innings in a meaningless game, you need to set the TPC and MPC a lot lower. I usually use 40 and 50 at this time for starters, 30 and 35 for long relievers, 15 and 20 for setup and closer with the call bullpen set to 3. This allows for pitchers to get into the game.
To get more position players into the game, lower runs setting in the Managerial Settings. What you are looking for in Spring Training is about 25 or so ABs for your actual ML players. Catchers should be about 20 as a lot of them are at the bottom of the order. Starting Pitching about 10 Innings worth of work, Long Relief about 7 innings and short relief about 5. Closer may only get 3 or 4 innings which is cool.
The big thing is not to forget to change all these settings again before the first regular season game.