Also called Great White, Da Bai is located on the Large Intestine meridian just below the divot at the head of the 2nd metacarpal bone.
This point is used in conjunction with Ling Gu. The line diagram shows you where the point are located.
Now here is the important part: if you want to needle it correctly, you place the patient's hand in this position - "standing" on the Small Intestine Channel with the Ling Gu and Da Bai Points facing up toward the ceiling.
Needle this point underneath the bone and slide the needle toward the Small Intestine meridian. You may need to massage the point and have the patient do a long slow breathing and strong exhale exercise as described in the write-up on Shang Liu.