From the top menu, select 'File --> Statistics'. You'll see 'Stack mode' at the top of the Statistics dialogue window. Select 'Median' from the drop down menu.
Load your images into Photoshop
Browse for your files, select them all, and hit Select and then OK. Then sit back and let Photoshop do all the hard work for you!
Remove any people that remain
Use the clone brush to edit out any leftover people or loose limbs that the photo stacking didn't fix.