How do I maximize window after I've minimize them?
The only way I know of is to get into Exposé mode (e.g. press (fn +) F3 on newer keyboards) and then pressing the down arrow key. You will see the currently selected minimised window (in the lower third of the screen) surrounded by a blue shadow and you can select other windows by moving around with the arrow keys. You can then bring any window to the foreground by hitting return.
beside Asmus Solution you can use cmd+tab to find your minimize software's windows after you go on select windows hold option and release all the key.