You need to first approximate the pH of the unknown solution using litmus paper so you can determine which indicator would be best for you to use. For example, if the litmus test showed a pH of about 4, you would use bromocresol green as your indicator. Pour the unknown solution into the beaker and record the volume. Pour the known solution into the burette and record the volume. Drip a couple drops of the indicator solution into the beaker. Before starting the lab, make sure there are no air bubbles in the burette.
Slowly begin to drip the known solution from the burette into the beaker. Pay close attention to the color of the solution, because when the reaction is complete the indicator will change the color. For example, bromocresol green will turn from yellow to blue to denote a completed reaction. As soon as the color changes, twist the burette knob to stop it from dripping any more.
Record the volume of known solution that was dripped from the burette into the beaker. Multiply this by the concentration of the solution and then divide by volume of the unknown solution in the beaker. This is the concentration of the unknown solution. For example, if you used 25 milliliters of 2.4 molar base to neutralize 10 milliliters of acid, you would multiply 25 times 2.4 and then divide by 10 to determine that the unknown solution's concentration was 0.6 molar.