To insert the micro-SIM:

1. The SIM card tray is found on the left side of the iPad (and the right side of an iPhone 4) which has a small hole near it.     Inside the hole is small button which helps to eject the SIM card tray out of the iPad.

2. Look in your iPad box for a SIM card eject tool. (You can also substitute this with a paper clip).

3. Insert the sharp end of the tool inside the hole.

4. Make sure the tool is straight and press firmly and gently so that the tray pops out completely.

5. Put the micro SIM card inside the tray and push it back inside so that you hear a slight click sound.

To remove the micro-SIM, just repeat steps 2-4.