Hello people i need some help

[font=Microsoft Sans Serif]hello people first POST yay any way i need some help i have been making 2 games which will be put to gether at the end bu that dosnt matter i just have 3 questions

  1. first of all and probebly the most important
    how do you make it so that the mouse cant
    leave the stage?
  2. how do you ad depth to things…
  3. finaly how do you make the background move with the mose but stop at a sertain point like in this HERE and yeh… so please help me