Open Your Anti-Virus Program
You can simply double click by keeping your mouse cursor on shortcut of your anti-virus program either located on your task bar on the right side or on your desktop. Sometimes you can find the shortcut of the program at both places, so just double click by placing cursor of your mouse on any of them.
Access Check for Update Option
Once you double click the anti-virus program, locate the Check for Updates option on a panel of the window that pops up, either on its left side or right side. Double click on it.
Access Website for Updates
Once you double click on the option of Check for Updates, it will take you to different websites for downloading the updates. Select the website you trust and start downloading the updates.
Update and Scan
From the website you select for updates, click update tab and wait for completion of updating all new virus definitions. After you are done with the updating process, you should restart your system and scan it.