Mac mini i7 2012 roll back to mavericks

Being my first post Pls be kind.
I just bought a new mac mini i7 2.3 with 4gb ram ,2012 edition. Never used mac before so it was a big decision not only as a concept but as a badjet since I bought also a Dell monitor. still having dell 7110 laptop with win7
All so far very good response for Bluetooth keyboard and Logitech mouse recognized out of the box .
Two days ago it show me the option to upgrade to yosemite .
I thought, OK 2014 OS it should be better than 2011 (?) and I upgraded.
I have lost the very good response and the mac mini became slow.
What should I do ?downgrade to mavericks? Or upgrade the ram ? (Expensive option)
If downgrade to mavericks how should I do that?

Thanks for your time and sharing your opinions

Good day folks
Since I am not able to find mavericks on app store and I wouldn't touch torrent for such think I am asking if some has the willing to help me and upload to Internet drive the mavericks in order to download


Thanks

Thanks for info let tell i what I did . I reboot and press command +r and gave me options. I choose reinstall i gave the pass of the WiFi and next it shows me the logo of yosemite not mavericks. Where I do something wrong?

Should I proceed further than the logo screen of yosemite?

Good day jbarley. You where right, did what you describe and it took me to Internet recovery and went through with mavericks installation.
THANK YOU one more time