Starting to train players who are already 21 won't go very fast. Like has been mentioned.. if you really want to train a player then get an nice 18 yr old with good potential and do mostly one position training. You are in D.V and there should be no reason that you can't promote within the next season or two. And once you get to D.IV your current players will be horrible even if you "train" them as you planned. Your best bet would be to buy players some players, since you should be able to get way better players that what you have for a reasonable price. Trust us.. We've all been down in the lower division and if you want to get to higher divisions where there is actually competition, then your current players won't help much.