This is the same window for Photoshop or Elemnents.
Make sure the Constrain Proportions box is checked, and the Resample image is checked and set to Bicubic. Enter the size you want the image to be, in most cases for the web and email I use 800x600. So you would just enter 800 in the with and the 600 will be auto entered in the height. Now click OK.