Hi Wendy,
What scott_7723 says is correct. In order to specify the device and channel to use in a VI or executable, you can use the DAQmx Physical Channel control on your Front Panel. This will be wired into the "physical channels" input to the DAQmx Create Channel.vi on the Block Diagram.
Hopefully this will get you going in the right direction! If you have more trouble with this, I would like to recommend that you create a new thread on the forum. Because this thread is older, a new one will better help the entire community to support you!
Cheers,
Brian A.
National Instruments
Applications Engineer