First, you should open the program and go to the Tools tab. Find Optimize PDF and click it.There is a Reduce File Size drop-down list in the toolbar. Select Reduce Multiple Files.Then you should choose Add Files > Add Files in the Arrange Documents dialog box.Select and add files you want to compress.When you have selected and added the required documents, select Open, and then click OK.The next step is to specify the compatibility version. When you're done, click OK.Open the Output Options dialog box. Select folder and filename, and then click OK.