Use Firefox if you want to stay with 10.6. It is still being updated.
Firefox
Will that automactically also update iTunes?
Yes, iTunes will appear as an update.
Check that your computer is compatible with Mountain Lion/Mavericks/Yosemite.
To check the model number hold down the option/alt key, go to the Apple menu and select System Information.
Mac mini (Early 2009 or newer) model number 3,1 or higher
Your Mac needs:
- OS X v10.6.8 or OS X Lion already installed
- 2 GB or more of memory (More is better - 4 GB minimum seems to be the consensus)
- 8 GB or more of available space
Check to make sure your applications are compatible. PowerPC applications are no longer supported after 10.6.
Application Compatibility
Applications Compatibility (2)
Do a backup before installing.
If you can/do upgrade, I recommend you make a copy of the installer and move it out of your Applications folder. The installer self-destructs. The copy will keep you from having to download the installer again. You can make a bootable USB stick to install using this free program.
Bootable USB Flash Drive – Diskmaker X
One option is to create a new partition (~30- 50 GB), install the new OS, and ‘test drive’ it. If you like/don’t like it it, you can then remove the partition. Do a backup before you do anything. By doing this, if you don’t like it you won't have to go though the revert process.