The building instructions for the Humanoid Robot Model (also called AlphaRex) can be found in the Lego Mindstorms NXT software. The building instructions can also be found on the web from various third party groups. Active-robots.com has building instructions for the Humanoid Robot Model (AlphaRexa), as well as other models, located here.
For the autonomous exploration project the ultrasonic sensor must be attached to the model. The example assumes that the touch sensor is connected to port 1, the sound to port 2,the light to port 3 and the ultrasonic sensor is connected to port 4 of the NXT control brick.