I think I have a Virus, not sure. Safari won't open

I have a MacBook Pro and lately it has been moving extremely slow, safari closes without warning (since yesterday it won't open at all--it closes immediately, and even my Microsoft word closed unexpectedly on me last week. I, too, downloaded free_game_bar.pkg, and I tried to follow advice given to someone else, but it doesn't seem to be working for me. The truth is that I don't know what is wrong with my laptop, I just know that something is wrong. I got a Mac because everyone said it is practically foolproof, well I'm the fool that has screwed it up. Can you help?

Sincerely,
Shana


P.S. Please consider my knowledge of computers as basic--beginner's level

Please download PCTools iAntivirus

• Open iantivirus.pkg
  
• Follow onscreen instructions provided by the installer.
  
• iAntiVirus will load automatically after installation has completed and is
  also available from Applications > iAntiVirus.
  
• Do a scan, and post any results in your next reply.