You will be amazed at just how easy it can be to keep your pool sparkly and clean. As you have probably noticed, almost all of us have contracted Sparklypoolitis.
You will need a test kit (see
http://www.tftestkits.net for the best value choices out there).
As you read here, start a Pool Book. Print out things from the Pool School. Make notes of the specifics for your pool. Get familiar with the Pool Calculator and the Chlorine/CYA chart -- bookmark them. If you have chemicals on hand, do the research to find out what these things actually do and what their ingredients are. Start a phone list of who carries the chemicals you need and call for price comparisons, we are all about doing this economically. Record your test results and what you did in response and why. Just like recording miles per gallon on your car, reviewing this can warn you when something is starting to go wrong.
It may be that a lot of what you got at the pool store is usable, maybe not, probably not, but don't worry about it. The key to it all is that going forward you will test, accurately and frequently, and then you add (or subtract) according to what you pool requires.
For example, I still buy things from pool stores. I have calcium increaser, tabs for the automatic chlorinator, cal-hypo "powdered shock", liquid "pool shock", and maybe stabilizer/conditioner buried in there somewhere. I also buy bleach and muriatic acid from the grocery stores, from the hardware stores, from the big box retailers.
So, to begin. Order a test kit. Start reading Pool School, then read it again. Get good test data and post back on this thread exactly what you know. And how you know. Start playing with the Pool Calculator to understand it. When you have reliable tests you will use it to see what you need to do and we can tell you what to do first. We love photos too.