The "Layers" panel on the right is showing a "Background copy" - I did this to give me a transparent background. If you work directly onto the original Background layer the canvas takes on the colour of the background a solid tone of black, white or whatever you choose. I prefer to be more flexible. With Background copy you can reposition it, put a border all the way round and so on. If you click on the Background in the layer box and highlight it you can add a new layer which will become the base layer. This layer can be filled with a colour ot a pattern to make a border. If you want a border dont forget to cange both the width and height measures when changing the canvas size. I prefer to work with image files at the original size (full size camera original) as retouching is more accurate. When you have finished all the steps then crop and change pixel depth at the end. If your intention is to prepare an image for the web it doesnt need to be any bigger than a normal full screen size - about 1000pixels wide. If it is going in a blog it will be displayed smaller than that anyway, only going to full size when it is clicked on.