Here is the easier way. As I can understand you got past step 2.
Libflashplayer.so file should be stored in one of those two directories or maybe in both (/opt/netscape/plugins/libflashplayer.so or in
1. Start console and login as root to get this # sign at the end fo the line (su- hit enter and then enter your root password).
2. If your libflashplayer.so file is stored in /usr/lib/nsbrowser/plugins then copy this line into your console and press enter
cp /usr/lib/nsbrowser/plugins/libflashplayer.so /usr/lib/opera/plugins/
the other possibility is that libflashplayer.so is stored in /opt/netscape/plugins/ then copy this line into console and press enter
cp /opt/netscape/plugins/libflashplayer.so /usr/lib/opera/plugins/
If it is stored in both directories it doesn`t matter from which one you copy the file, just choose one.
By following what is written above you can skip step number 4.
Step 5 is a bit modified, here is the right path
5. open opera go to tools ----> preferences ----> advanced----> content ----> click on plugin options ----> click change path
Everything else should work with no problems