The obvious answer is – read the manual.
I am not being rude, but since you failed the simple test of including both the operating system and the name of the anti-virus package, then it is impossible to give specific instructions.
Many AV companies produce AV software for different platforms such as Windows PCs, Linux PCs, Apple PCs, various tablets and smart phones. These different versions are installed and operate in different ways, which is why the missing information is so important when asking questions like this.
I hope this helps you ask the right sort of question in future.
Buy it, install it on your computer (either the download or the CD version). Usually it will start itself, and ask if you want to scan your computer. You can also open the program (it should put an icon on your desktop) and choose to have it scan your computer at startup, or at a specific time of day when your computer is on. Antivirus programs (like McAfee and Norton) will run in the background, so you don't have to do anything else. Just enjoy your surfing.
if you have bought a anti virus disc from a store or online download it to your computer after if is downloaded start you scan in it will scan your computer for virus read the instruction on the booklet it give you
Might want to tell us which one you're using – they're all different in their interface.
first install in your pc