For antivirus, just use Microsoft built in AV if you are running 8 or higher, its excellent. For anti-malware which is what you're really going to need, I recommend malwarebytes paid version. I also recommend using Google chrome or Firefox and using adblock plugin. Also password managers are useful for protecting your accounts, lastpass is awesome. Finally turn up user access control(UAC) in Windows control panel under user accounts. Yes I know it's annoying at first, but read the messages and you can block everything you don't want, I run zero antivirus on my computers thanks to this, but I don't recommend that for you! I've worked in IT 12 years now so I know what I'm doing. Be safe. Also make sure to keep your Windows up to date.