If you are having problems uploading images check the following:

make sure your image file is not too big. the website automatically 'downsizes' images to fit, however it can get a bit sticky with very big files. try to make your image less than 1m (typically images for web are 72dpi). 

make sure you have clicked the 'submit' button at the bottom of the page after you have uploaded the image.

you will need to be logged in to submit images.