How do you get an antivirus software on a windows from a mac?

I have a desktop with NO internet but it did before, I am trying to play my games but, when i go to play 30 minutes later a blue screen comes up and shuts down my computer saying it is under risk or something.. I am thinking it needs a BETTER virus protection because of what had maybe been installed on it before.. What is the best virus protection to use for windows that is FREE!?? Also, How can I download it from my mac onto my USB drive and then onto my windows?? All answers are appreciated!

How do you get an antivirus software on a windows from a mac?avast

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How do you get an antivirus software on a windows from a mac?ducati

The best free antivirus is AVG. you can also try out the trial versions of nod32 and kaspersky. just google it download it, transfer to the usb and then to the desktop machine.
one way is to use a usb memory stick and dnlaod the anti-virus file onto that, then put the stick into the windows usb port and install from the stick.

Make sure you dnload a windows version of the software....I use AVG antivirus and they do have a free version