help getting rid of system security

I am very technology impaired. My son directed me to you. I am having problems with System Security 2009 taking over my computer. I downloaded the malwarebytes (I think) but couldn't find it in the program file to rename it to winlogin. now what?

Please download the current version of HijackThis from HERE

• Double click and run the installer.
  
• It will install to C:\Program Files\Trend Micro\HijackThis\hijackthis.exe
  
• After installing, you should get the user agreement, press accept and Hijack This will run.
  
• Select Do a system scan and save a log file. This will open a notepad file of everything Hijack This found, copy and paste it back here.