• Open the image and rotate it as necessary
• Resize the image
  • Click Image→Image Size…
  • Enter a width of 500 pixels, the height should change automatically.
  • Click OK
• Save for Web
  • File→Save for web…
  • Choose JPEG and Maximum from the dropdown options.
  • Click OK and save the new image in a place where you can easily retrieve it for uploading.

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• Open the image and rotate it as necessary
• Resize the Image
  • Image–>Scale Image…
  • Enter a width of 500 pixels
  • Click Scale, the height should change automatically.
• Save the Image
  • File–>Save As…
  • Rename the file appropriately
  • Expand Select File Type (By Extension)
  • Select JPEG image
  • Click Save
  • Check the box Show Preview in image window
  • Move the slider to the desired quality (I like 95 or better)
  • Click OK