A couple tips:
Once you get some CYA in the water, you’ll want to increase your FC to follow the
FC/CYA Levels. The CYA protects the chlorine from the sun but it also holds some in “reserve” lowering the effective/active concentration.
Also note that you don’t have Bromine (Br) in your water, unless you added it. And you don’t want to add it. That test gives you the Chlorine (Cl) or Bromine reading (Br), but it’s a one or the other. So for your purpose it’s the Cl number you care about.
Once you get the hang of things, you’ll use that Cl block test as basically a quick check that you have some Chlorine in the water. For accuracy stick with the FAS-DPD (powder/drop) chlorine test.
Have another read through
ABCs of Pool Water Chemistry now that you’re starting to get the hang of things; it might start to make a little more sense.