Using the toolboxThe first time you start the application, the toolbox appears on the left side of the screen. Some tools in the toolbox have options that appear in the context-sensitive tool options bar. These include the tools that let you use type, select, paint, draw, sample, edit, move, annotate, and view images. Other tools in the toolbox allow you to change foreground/background colors, go to Adobe Online, work in different modes, and jump between Photoshop and ImageReady applications.
For more information on the foreground and background color controls, see Choosing foreground and background colors.
Using the tool options barMost tools have options that are displayed in the tool options bar. The options bar is context sensitive and changes as different tools are selected. Some settings in the options bar are common to several tools (such as painting modes and opacity), and some are specific to one tool (such as the Auto Erase setting for the pencil tool).
You can move the options bar anywhere in the work area, and dock it at the top or bottom of the screen.
To display the tool options bar:
Do one of the following:
Choose Window > Options.
Click a tool in the toolbox.
Lasso options bar
To return a tool or all tools to the default settings:
Do one of the following:
Click the tool icon on the options bar, then choose Reset Tool or Reset All Tools from the context menu.
(ImageReady) In Windows or Mac OS 9.x, choose Edit > Preferences > General, then click Reset All Tools.
(ImageReady) In Mac OS X, choose ImageReady > Preferences > General, then click Reset All Tools.
To move the options bar:
Drag the options bar by the gripper bar at its left edge.
Choosing foreground and background colorsPhotoshop uses the foreground color to paint, fill, and stroke selections and the background color to make gradient fills and fill in the erased areas of an image. The foreground and background colors are also used by some special effects filters.
You can designate a new foreground or background color using the eyedropper tool, the Color palette, the Swatches palette, or the Adobe Color Picker.
The default foreground color is black, and the default background color is white. (In an alpha channel, the default foreground is white, and the background is black.)
Source: Photoshop Help