The general layout of the SQL Developer window is a left pane for navigation around objects, and a right pane to display and enter information. In the figure, the left-hand pane shows that a connection has been made to a database. The connection is just a label chosen when the connection was defined, but most developers will use some sort of naming convention. The branches beneath list all the possible object types that can be managed. Expanding the branches would list the objects themselves. The right-hand pane has an upper part prompting the user to enter a SQL statement and a lower part that will display the result of the statement. The layout of the panes and the tabs visible on them are highly customizable.
The menu buttons across the top menu bar give access to standard facilities:

• File A normal Windows-like file menu, from which one can save work and exit from the tool.
• Edit A normal Windows-like edit menu, from which one can undo, redo, copy, paste, find, and so on.
• View The options for customizing the SQL Developer user interface.
• Navigate Facilities for moving between panes and for moving around code that is being edited.
• Run Forces execution of the SQL statements, SQL script, or PL/SQL block that is being worked on.
• Debug Rather than running a whole block of code, steps through it line by line with breakpoints.
• Source Options for use when writing SQL and PL/SQL code, such as keyword completion and automatic indenting.
• Tools Links to external programs, including SQL*Plus.
• Migrate Tools for converting applications designed for third-party databases (Microsoft Access, SQL Server, and MySQL) to the Oracle environment.
• Help It’s pretty good.

SQL Developer can be a very useful tool, and it is very customizable. Experiment with it, read the Help, and set up the user interface the way that works best for you.

Reference:

• OCA Oracle Database 11g: SQL Fundamentals I Exam Guide (Exam 1Z0-051)