The post processing has already been covered in this thread, the gist of it is that PS can do HDR, but the more dramatic types of HDR tone mapping are usually achieved with photomatix.
The exposures themselves might be easy or not depending on which camera you have. The A series canons can do manual exposure without too much trouble, but the smaller elph series can only adjust exposure (what you want is control over the shutter speed only, not the shutter and aperture combined...you may be able to get decent HDR images with an elph, but most of the time the aperture will vary and the depth of field will differ, giving you a lousy result). auto-bracketing while in shutter priority mode is the most convenient way to achieve this, if the camera allows. The standard starting point for HDR seems to be 3 exposure auto bracketed +-2.0EV. This is a good place to start, and auto bracketing also means you can use a remote or at least gingerly touch the shutter release. If you have to adjust all sorts of settings by hitting buttons it's pretty hard to keep the camera in the exact same position on the tripod.