The following subpages will go through the various tools that you can use in Photoshop. These include the Selection Tools and the Editing Tools, as well as a primer on the options tab.
This video is a long but thorough tutorial that will give you an overview of the basic design tools in Photoshop.
Note: Although the below video says the version is CS6, the tools are in the same general place from version to version of Photoshop.