I'm confused about all the various things that seem to go with changing + change pads and need some help!

I am going to get something like this to put on top of a dresser http://www.amazon.ca/dp/B00O64QJOC

It seems there are also then sheets like this to cover it

And these change pads

And liners!

How do you use all these things together? And which do you actually need/did you use for your changes? I'm assuming those individual changing pads are useful for throwing on the floor/couch/wherever, so those seem practical. Do I just throw those on top of the dresser pad and that's it, or do I need the sheet and disposable liners too?