Well, let's see if we can simplify this some for you.
Forget about all the chemicals!
From what I've seen, these chemicals are designed for the general public looking for a quick fix when they don't understand about cycling a new fish tank.
Now this might very well include you, especially if you have not read the link An t-iasg gave you.
Under the assumption that you have NOT read about cycling a new fish tank... here's the short and skinny on it. Fish produce ammonia. Ammonia is dangerous to fish. Over time, a fish tank will naturally grow a bacteria that converts ammonia into nitrite. Nitrite is dangerous to fish. Over time, a fish tank will naturally grow a bacteria the converts nitrite to nitrate. Nitrate is safe for fish at moderate levels.
Cycling a fish tank is giving the tank and its filter time to build up these needed bacteria. But it's a process that can take a month or more. In the mean time, do PWC daily to keep ammonia and nitrite levels low until the tank finishes cycling. After that, you'll only need to do PWC weekly or monthly to keep nitrate levels in the safe range.
At this point, the main thing you need to purchase is the Freshwater Master Kit by API (or its equivilent). This kit will include tests for ammonia, nitrite, and nitrate. You WILL use these tests every day while the tank is cycling. By watching the levels of ammonia and nitrite, you can guage how much of a PWC (0, 25%, 50%) you need to do today to keep the ammonia and nitrite levels down (like around 0.25 ppm).
When it comes to chemicals, there's really only one that you want to consider: Prime by Seachem (or some similar water conditioner). Assuming you are refilling with tap water, you need a conditioner to neutrilize things like chlorine found in most city water.