A method of enabling user interaction with computer software executed in a computer system using an interface surface including information relating to the computer software. The interface surface includes a plurality of regions, each having coded data indicative of a plurality of reference points and an identity of the region. The user uses a sensing device to capture images of the coded data, identify and decode the coded data from the captured images, and then generate indicating data indicative of an identity of the region and movement or a position of the sensing device in the region. The computer system uses the indicating data to operate the computer software at least partly in accordance with instructions associated with the region.