To add an image in Version 5, navigate to the page you wish to add an image
to and open the editor. Go here to see how to open the editor.
Find where you want to place the image within the content and click there. Then click the second icon from the left (looks like a mountain and sun picture). A new window will pop up. Click the Upload an Image link on the left, then the Browse button on the right. Find the image you want to upload and select it. Then press Upload File on the lower left of the window.
Once it has uploaded, you may need to resize it. If this is an image straight off a camera it will be very large and take a long time to load. Simply type in a new width for your image in the New Image Width box. As long as you don't press Resize Original Image, you will be able to change the width of the image repeatedly, in case it's too small or too wide for your page.
Click Save & Close, then Save & Close again on the main editor and your image will be there!