Pencil Tool: This tool is normally used to creat little dots in a image. It works about the same as the brush tool.
Eyedroppen Tool: With this tool you can set your foreground color. In you own image, click the coloor you want to have.
Vertical Type Tool: This tool is used to put some text in an image. It will write vertical (like the name suggests).
Screen Modes: Use these buttons to select your screen modes (standerd/fullscreen with bar/full screen).