Most user have a friend that has a Mac or hackintosh or use a a Mac at a local school, public library or university/college. You'll have to open your own Apple Mac App Store account with a credit card to download apps; don't use your friend's account. On the other Macs (school, etc.) you may have to get permission to download Sierra and UniBeast, and then to run UniBeast.
Otherwise, you'll need to follow
https://www.tonymacx86.com/threads/simplest-mac-os-x-installation-guide.60255/
Be advised that we don't tolerate piracy on this forum (see the Forum's Rules). Apple only authorizes it's MAS to distribute the OS X (macOS) products.
Good Luck! Welcome to the Forum!