I want to use the raspberry pi to send values to the Oracle11g database, but when I run import cx_Oracle syntax for that process, I get the following error: 
It means, that you have not installed module cx_Oracle.
First you must install Oracle driver with PIP:
python -m pip install cx_Oracle --upgrade
Hope it helped you.
There is no ARM port of the Oracle Client libraries that are needed by cx_Oracle. You'll have to use something like REST calls from Python to a mid-tier server (in whatever language you like) running on an operating system that will support connection to the Oracle DB.