How to install Oracle Application Express 4.2

Installing Oracle Application Express (APEX) 4.2 follow below step.

 1. Download Oracle Apex4.2.zip
    from  http://www.oracle.com/technetwork/developer-tools/apex/downloads/index.html

 2. Unzip downloaded zip file:
   

    UNIX and Linux: $ unzip apex_4.2.zip

    Windows: Double click the file apex_4.2.zip in Windows Explorer

 3. Change your working directory to apex.

 4. Start SQL*Plus and connect to the database where Oracle Application Express is installed as SYS specifying the SYSDBA role.
    For example:

    On Windows:

    SYSTEM_DRIVE:\ sqlplus /nolog
    SQL> CONNECT SYS as SYSDBA
    Enter password: SYS_password

    On UNIX and Linux:

    $ sqlplus /nolog
    SQL> CONNECT SYS as SYSDBA
    Enter password: SYS_password

 5. Full development environment. Run apexins.sql passing the following four arguments in the order shown:

    @apexins.sql tablespace_apex tablespace_files tablespace_temp images

    Where:

        tablespace_apex is the name of the tablespace for the Oracle Application Express application user.

        tablespace_files is the name of the tablespace for the Oracle Application Express files user.

        tablespace_temp is the name of the temporary tablespace or tablespace group.

        images is the virtual directory for Oracle Application Express images. To support future Oracle Application Express upgrades, define the virtual image directory as /i/.

    Example: @apexins.sql SYSAUX SYSAUX TEMP /i/

    For Runtime environment, @apxrtins.sql SYSAUX SYSAUX TEMP /i/

 6. To change the password for the ADMIN account:
   

    a. Change your working directory to the apex directory where you unzipped the installation software.

    b. Start SQL*Plus and connect to the database where Oracle Application Express is installed as SYS specifying the SYSDBA role. For example:

        On Windows:

        SYSTEM_DRIVE:\ sqlplus /nolog
        SQL> CONNECT SYS as SYSDBA
        Enter password: SYS_password

        On UNIX and Linux:

        $ sqlplus /nolog
        SQL> CONNECT SYS as SYSDBA
        Enter password: SYS_password

         Run apxchpwd.sql. For example:

        @apxchpwd.sql

        When prompted, enter a password for the ADMIN account.

More details ...
http://docs.oracle.com/cd/E37097_01/doc/install.42/e35123/otn_install.htm