Mount the windmill to the end of the aluminum pipe. This will probably be done with included hardware, but it depends on what comes with the windmill. Consider using zip ties, or cable ties, to reinforce the mount.
Attach a wire to the windmill using electrical tape. The windmill probably already has leads coming out of it; check the directions specific to your windmill.
Mount the aluminum pipe to an exterior wall of the house where the eaves are flush with the side. For wood frame houses, find a stud in the wall using the stud detector, drill pilot holes, and screw the brackets into the wall. Masonry houses require a different drill bit and different screws. Allow the aluminum pipe and the windmill to extend a few feet above the level of the roof.
Run wire down the pole, securing it with zip ties. Incorporate power from this wire into the energy needs of your house. Perhaps this wire will lead to a pool heater, or perhaps it will lead to a system of batteries where power can be stored.