Force.com IDE Developer Guide

Force.com IDE UI Overview
Force.com Toolbar Buttons
Package Explorer
Force.com Context (Right-Click) Menu
Force.com IDE Editors
Schema Explorer
Force.com Wizards
Force.com Views (Tabs)
Getting Started with the Force.com IDE
Developing with the Force.com IDE
Testing Code with the Force.com IDE
Deploying Code with the Force.com IDE
Getting Started with the Apex Debugger
Useful References
PDF

Package Explorer

The Package Explorer provides a hierarchical tree view of the projects and files in your workspace, and works just like the standard Eclipse Project Explorer. The Force.com IDE provides additional menu options; for details, see Force.com Context (Right-Click) Menu.The Package Explorer tree view with the src/objects folder open and the Mileage custom object highlightedFor information on standard project folders and files, see Force.com Project Basics.