Well, where to start? I guess the beginning is a good place, huh? This is going to be a long post, I see.
The cycling of any aquarium is a basic necessity. It occurs naturally. The conditions of any living area, aquatic, terrassic, or atmospheric, is a delicate balance. All living creatures, or plant, need certain conditions in which to survive. One condition is a clean environment, at least relatively speaking. What may be "clean" to one species, however, may be deadly to another.
The relationship of aroebic bacteria and aquatic life is an example of the coexistence of two life forms that benefit each other. Fish provide a material, wastes, that need to break down, the job of the bacteria. And the bacteria break down the poisonous elements into those that will not harm the fish and are beneficial to plant growth. An imbalance of any one contributor to this ecologic biosphere will have negative results. Over feeding, for example, can over load the capacity of the bio bed and cause a spike in ammonia, nitrate, and nitrite. Bad for fish. Having an insufficient bio-load can lead to a drop in beneficial bacteria. So, as you can see the balance is delicate. The great thing about nature is that it seems to be able to balance itself, if given time.
There are basically two cycling methods, fishless and with fish. The terms are basically self explanatory. With fish, you add a small group of hardy fish to provide a supply of waste to start the bio loading of the tank. This provides the "food" for your bacteria. It will speed up the process but does have draw backs. One, it does stress the fish. You will have spikes in ammonia, nitrates and nitrates during the process. It is faster that some fishless cycles.
Now comes the complicated subject, fishless cycles. With fishless cycles, there are basically three categories, normal, accelerated, and forced. Normal, you set your tank up and let nature take its course. This process takes the longest. Some tanks can take as long as 12 weeks to cycle, especially the larger ones. Fish may be added gradually, emphasize gradually, as the process winds down. That will be explained later.
Accelerated cycling is using "seasoned equipment, substrate, or decorations. This method uses a pre-colonized method that already has bacteria present. Thus, hastening the establishment of a bacteria bed. This can also be used with the first method mentioned.
Forced is using chemicals, which I do not recommended to the beginner. I do use this method when taking fish to large, multi-day shows and conventions. I am not proficient at this method. I have some very good friends that aid my in this. They use ammonia. That's right the same ammonia that kills fish. They inoculate the tank with ammonia. I do use seasoned equipment and gravel. Some of my tanks will cycle in 24 hours. This is an exception and not the rule. I do know that a small capful goes a long way. But these folks use syringes to determine the amount of ammonia to use. Too complicated for this old fishkeeper. Again, using seasoned equipment and gravel to seed the bio-bed definitely speeds up the process.
As far as water changes, during the cycling period, I change 25% daily. After the tank establises itself, I change 25% minimum weekly.
One thing I cannot over stress is the virtue of patience. Do not assume anything. Let nature take its course. In fact, tattoo this on your forehead, "BE PATIENT".
Now, to finish this off. No matter which method you use, taking samples and testing the water is a must. When setting up a tank, I take a water sample right after adding the water to use as a benchmark. Samples are taken daily for 2-3 days. After that, twice a day until the tank has cycled. The readings will let you know. Expect ammonia spikes during the process. Get a good test kit, not a strip kit. A good quality "liquid" kit will run about $25-$70.
Now that I've totally confused you, good luck and happy fish keeping.