Instructions
Insert "The Sims 2" disc into your computer's disc drive, and click the Sim household you wish to play in the game.
Click "Build Mode" in the bottom left corner of the game's screen, and click the staircase icon in the bottom right corner.
Click the staircase you wish to use for your household. If you have enough funds to purchase the staircase, it appears next to your mouse's cursor.
Move the staircase to an area in the game that is clear of objects and Sims.
Click the area with your mouse to place the staircase in the position, or hold down the mouse's click button and move the mouse clockwise or counterclockwise to rotate the staircase.
Click "Live Mode" in the bottom left corner of the screen to resume playback.