First of all, hello to everybody! I'am new member here!..
I woud like to import some default sounds from my older symbian phones to my N9, is this possible? Thanks

Welcome!

If you can find the sounds on your symbian device and somehow copy them to pc (I assume you can use x-plore to copy them to E: and then trasnfer them to your pc by mass storage mode) then you can just copy them to mass storage again in the N9 Music folder. From there you can assign them as tones via settings.

From memory, its something along the lines of:
Using navifirm, download the rofs2 of a specific handset
Using nokia firmware cooker, extract the rofs2 to your pc
Find the audio files and copy them to your n9.

Or, if you have a hacked symbian handset, just copy from z: to e: and connect your phone as mass memory. On your pc, copy them to the n9.

Download xplore and install it. its free and will also installs on not hacked devices. after installing open xplore from menu, when it starts, go to its settings or options and check mark show rom drives and also tick mark show hidden files and folders if not already marked. after that come back close settings and it will show two more drives i.e D and Z (i think).

after that navigate to Z:/data/sounds if there is no data folder in Z then look for it in C drive. there should be a drive called Data. there are placed all sound files for your symbian phone. you can also send them to your N9 via bluetooth or just copy them to your MMC and then transfer them to your N9. Good Luck