Underneath the Navigation bar, is the Tool Bar, which shows you which tool you are using, and the options available for this tool. The default tool is the paintbrush.
On the left side, you have your tools palette, which has all the basic tools available in photo editing software such as Marquee, Move, Lasso, Crop, Wand, Clone, Pencil, Eraser, Brush, Gradient, Paint Bucket, Text, Hand, Zoom, and Foreground/Background Colors. There are also some handy tools that are usually part of another tool or function in some standalone image editing software such as Blur, Sharpen, Smudge, Sponge, Dodge, Burn, Red Eye Reduction, Drawing, Bloat, Pinch, and Colorpicker.
Since you are using an internet connection and mouse, some of the photo editing tools may not operate as smoothly as expected. The Smudge tool, for example, is a little difficult to control on older computers and those with slower internet connections.
On the right side, you have the Navigator, which sets the viewing size of your photo; the Layers palette; and the History box, which will show you each action you take while editing your photo.