[header] How to block other computers from being able to access your computer's printer and files over the internet [title] Choose your anti-malware program. [step] There are dozens of programs you can choose from. Many are free, but if you're willing to pay for the program, you can get a more advanced program. 
All of them can run a scan that detects a large majority of threats to your computer. The more advanced programs allow you to do a custom scan.