First step: find and follow the right steps

Avast Professional Edition

Full-featured antivirus software. Better than our free antivirus, especially for web surfing, but without the firewall and antispam included in avast! Internet Security. Also if you wish to customize your security, this is the recommended software.

Avast Home Edition – Free Antivirus

Avast! Free Antivirus often outperforms the competitors´ paid products and is the minimum protection you should have — it provides great protection against viruses and spyware.