There are four tools available for selecting an area within your image, three shape selection tools and the Magic Wand selection tool.
Rectangle SelectYou may use this to define a rectangle or square selection region. For greater discussion of how to use this tool, please visit the Shape Selection Tools section.
Lasso SelectYou may use this to draw a freeform selection region. For greater discussion of how to use this tool, please visit the Shape Selection Tools section.
Ellipse SelectYou may use this to draw an ellipse or circle selection region. For greater discussion of how to use this tool, please visit the Shape Selection Tools section.
Magic WandYou may use this to select areas of the active layer that are similar in color. For greater discussion of how to use this tool, please visit the Magic Wand section.