Take a look at the Best Guess table in my signature below. It shows the correlation between your CYA level and how high you need to keep the chlorine for maintenance (minimum and maximum levels) and how high you need to take it to achieve shock levels if you have algae. Tell us the CYA level of your water and the volume of the pool and we can help you figure out doses of bleach to use.
If you don't already have a good test kit, it will make your pool care much easier if you will get one. The one we recommend is the Taylor K-2006 or 2006C (same kit, larger bottle of some reagents). If you buy it through the Amazon link in my signature, the Pool Forum makes a little money on the sale which helps us keep this form online. Only buy if the seller is Amato Industries, however. Some other sellers are substituting the K-2005 which you do NOT want.