Upgrade Oracle from the version 9 to 10

Hi!

We are planning a SAP-upgrade from 4.6c with Oracle version 9 to SAP EHP4.

The target oracle version should be 10.

Questions:

1) What is the procedure to update Oracle from version 9 to 10?

1a) where can I find the appropriate documentation?

1b) with which tool should this operation be executed?

Thank you very much!