When you say "transfer" I'm assuming this means that you do not wish to upgrade the database in place from 9i to 10g, but you wish to copy the 9i database to a 10g database.
The easiest way to do this (assuming the database is not very large) is to use the export and import utilities. First, you must create a basic 10g database. Then you would export the Oracle9i database, transfer the export file to the other server (assuming the 10g database is on another server, but it could reside on the same server), and then import the data into the 10g database.
For more information on using export and import, refer to the Oracle9i Release 2 (9.2) Database Utilities guide.
If I was incorrect in my assumption and you are planning to migrate the existing 9i database to 10g, the Oracle Database 10g Release 2 (10.2) Upgrade Guide provides several options for accomplishing this, as well as a detailed explanation of each option.
Dig Deeper on Oracle database export, import and migration
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