see my two links in my signature. in order to determine your required chlorine level you need to know your CYA level. the way to know your CYA level is to get one of recommended test kits (also a link in my signature). I think the TF-100 is the best value but you can decide that. once you have the test kit, we can help you!
welcome to TFP!
for now, do you have anything to measure chlorine levels???
if so, use the pool math at the top to figure out how much to add and aim for FC of 3 for now until you know your CYA