Long exposure for low light night photography requires camera stabilization. This statement goes double for HDR. Three or more exposures combined into a single blend involve a range of shutter speeds that would be impossible to hand hold. In addition, while HDR software such as Photomatix will align slightly offset hand-held shots, it is best to combine photos that are in perfect alignment.
HandlePod and HDR
HandlePod makes night HDR photography possible without a tripod simply by pressing it against any available solid object. As long as the camera is stabilized, any combination of exposures is possible. It is best to vary the shutter rather than the aperture which may change the depth of field. Experimentation is the key here. Adjust exposure settings manually rather than using the auto-bracketing feature of the camera. This applies particularly in low light situations where a wide range of exposures is the best option.
Information on HDR photography is widely available on the web. But all HDR tutorials advise camera stabilization to eliminate camera shake and maintain alignment among exposures. Combining the different exposures can be done with software like Photomatix or masking in Photoshop. Be aware that HDR tonemapping can result in oversaturation and obvious manipulation that has become a seriously overused. Try to achieve a more natural look or go for a black and white presentation as in the example above.