you need a few things. A reflective sphere (which you see in a few photos) to capture the lighting of the real-life scene which you want to composite your model into. Secondly you need a small program called HDRShop. Thirdly you need a massive program called 3D Studio Max, and finally you need a good renderer such as VRay. Then of course you need the tools to get HL2 models into 3dsmax: GFScape, a HL2 Model importer, and a texuture and model converter. If you ever happen to get all this stuff, tell me and I'd be glad to show you how to use it all!