The Set Tolerance page of the Cell Size wizard is opened when you click on the Next button in the Set Y Targets page of the Cell Size Wizard.
To enter the tolerances as a percentage, click on the % radio button. To enter the tolerances as an absolute value, click on the length unit (i.e. mils, inches, etc.) button. Whichever length unit is in use for this project appears here.
Enter the desired tolerance in the Tolerance text entry box.
When you are done defining the tolerance, click on the Next button to go to the Results page of the Cell Size Wizard.