"Shock" is a verb that means increasing your chlorine level to kill and metabolize anything that normal chlorine levels cannot.
Pool stores frequently sell what they label as "shock", which can be various forms of either powdered or liquid chlorine (essentially bleach, though frequently it's a higher concentration). Bleach is good enough.
But the Shock Level is determined by the level of stabilizer (Isocyanuric or Cyanuric Acid--CYA) in your pool. The more CYA, the higher the Shock level.
We have a table for that, called the "Best Guess" table. But you need to know the CYA level first. We always recommend a good test kit. Our first choice is the Taylor Technologies K-2006 or K-2006C. Our second choice, especially if you need it right now, is the HTH 6-way drop test kit which seems to only be available at Walmart. Both use the same CYA test. You may be able to find a stand-alone CYA test kit, but your pool store should be able to test your water and tell you. Testing yourself is best.

Best Guess table: http://www.poolsolutions.com/gd/best...ine-chart.html

Meanwhile, one 121 ounce jug of 8.25% regular unscented ultra bleach should add about 10.4ppm (parts per million--how we measure concentrations of everything but pH in pools) to your pool, which I estimate to be about 7500 gallons. To shock your pool, you may need anywhere from 1 to 2 to 2 1/2 jugs depending on your CYA level.