This IS THE FIRST TIME I EVER USED A Linux OS and I find confusing, specially updating applications such as Clamav?

If the distro you are using is one in which you install software from repositories rather than from third-party sources (most of them are) and you are using one of the major desktop environments, the distro will notify you when updates are available so you can install them.

Tell us which distro you are using and we will be able to provide more specific information.

It would be best not to do that in this forum, which is just for member introductions, but to open a thread in Newbie or in the forum for your distro.

There is a learning curve when you start using Linux. Linux is not hard, but it is different.

Welcome to LQ.

I got the application from the repository

Then your distro should notify you when updates are available.

You still haven't mentioned what distro, but try this: Go to your distro's home page and look for a link for "Documentation" or "Support," then use the search feature. There ought to be (famous last words, I know) an article or two about how updates work.

This link might help: http://www.linux.com/learn/tutorials...ng-your-system