Using litmus paper, you can determine what the approximate pH of the solution is. If the pH is less than 7, it is an acid, so you will need a base to neutralize it. If the pH is greater than 7, it is a base, and you will need an acid to neutralize it.
To perform a titration, you will need a beaker, burette, indicator, the unknown solution that is the subject of your experiment and an opposite solution. The known solution goes in the burette and the unknown solution is put in the beaker.
The indicator that is used depends on the pH of the unknown solution. Based on the litmus paper, estimate the pH and choose an indicator accordingly. For example, if the pH were approximately 8, you would use phenol red.
Slowly release the known solution in the burette into the unknown solution in the beaker. When the solution in the beaker changes colors, you will know the unknown solution has been neutralized. The color change will depend on the indicator used.
Multiply the amount of the known solution that was added to neutralize the unknown solution by the concentration of the solution, then divide it by the volume of the unknown solution that was used to get the unknown solution's concentration. For example, if you used 60 milliliters of a 3.0 M base to neutralize 90 milliliters of an unknown acid, multiple 60 times 3 and divide by 90 to get 2.0 M as the concentration of the unknown solution.