How to Connect to Oracle
Connecting to the database will require to enter the host, port, database user and password as explained in the Connection Dialog.You can connect to Oracle using the users 'sys', '/ as sysdba' or any database user. The default Oracle port is 1521.
From the Method & Driver combo you can choose between different connection methods.
In the Database SID field enter the Oracle SystemId, namely the Oracle instance. Default Oracle SID is ORCL. This identifies the database in case more instances of Oracle are running at one time. You can execute show parameter instance_name in SQLPLUS and see the SID as the last keyword is the list.

Connect to Oracle using Kerberos Authentication
This require setting in the Connection Dialog Settings pane the Properties field to:
oracle.net.authentication_services=( KERBEROS5 );oracle.net.kerberos5_mutual_authentication=true
Please also edit the file DbSchema.vmoptions ( look in the same folder as DbSchema executable or in DbSchema.app/Contents/vmoptions.txt ) and add this oracle.net.kerberos5_cc_name=path_to_credential
Guided Oracle Installation
Download Oracle 10g from: http://www.oracle.com/technetwork/database/express-edition/downloads/102xewinsoft-090667.html
Start the installation process...Select Next...Accept the license agreement...Select the destination folder:
Type in your password:
Install...