How do you turn off the pad when you are using a mouse? My fingers touch the pad and causes the cursor to move when typing.

How about an external mouse?
USB plugin?

There might be either a dedicated key somewhere on the laptop the turnes it off. If there is none then you should have a function key (F1 - F12) that disables it. These are the keys right at the top of the keyboard. The have dual function and should have a picture on each key with a green or purple colour.

Every laptop is different though. To access the function keys you must press the "Fn" key on the keyboard (between ctrl and Windows key) and the corresponding F key.

Dell has a utility that does disables the touchpad when it sees a USB mouse attached. What brand do you have?