Perform the following steps to configure the field update and complete the workflow:
Enter a Name and Unique Name for this field update.
Type the Description for the filed that you need to update.
Select the object for the associated field to update and click Next.
To re-evaluate the workflow rules on the selected object after the field update is done, select the Re-evaluate Workflow Rules After Field Changecheck box.
Under the Specify New Field Value section, select an appropriate options from the list of available options based on the Field to Update selection.