Make a copy of your original file and open the copy in Photoshop.
Go to the Image menu, then Resize, and click on Image Size...
The Image Size window will open. Set the width to 1400 pixels if your image is landscape format or the height to 1050 pixels if your image is portrait format (which mine was). Make sure that the dimensions of the image are locked by ticking Constrain Proportions to maintain the aspect ratio of the image.
Click OK and photoshop will then have resized your images.
Choosing a colour space
Your image should be saved with a colour space profile of sRGB.
To check how Photoshop Elements is using colour space, go to the Edit menu, then click on Colour Settings.
The Colour Settings window will open.
If you want to make sure that Photoshop converts (or keeps) the colour space as sRGB, select Limited Colour Management, or if you are printing your images then select Full Colour Management and this will retain the colour profile of the image.
You can see if your image has sRGB colour space when you save it as a new file.
Go to File and click on Save as. The Save as window will appear.
The ICC Profile should be ticked and be sRGB.
File names and file types
When submitting a file for a digital competition you should save the file in JPEG format, you should name it Title by Author.jpg for example:
My Photo by Joe Bloggs.jpg
If you're saving the image in Photoshop, it will offer a number of JPEG Options, make sure you save it as Quality12/Maximum.
Important note: This guide was compiled using Photoshop Elements 3.0, other versions may differ.