The following link may be helpful to you if you are using the ata as a sccp device. Keep in mind you must be running an sccp image on the ata.
http://www.cisco.com/warp/customer/788/voip/ata_sccp.html
For the secon part of your question. In order to find out the current ip address on the ATA, do the following.
1. Pick up the handset
2. Hit the button on top of the ATA
3. Dial 80#
Ademola
For general tips on configuring the ATA follow this link
http://www.cisco.com/warp/customer/788/voip/ata-faq.shtml