How do I download plug-ins from websites on ubuntu?

Can you give some SPECIFIC examples? What plug-ins? From where?

Can you access your Ubuntu Software Centre? Can it list the software available in each category or in search bar?

I can't directly download plug-ins from the internet. I can download thing from the Software Center. But I need to be able to download certain plug-ins from online. I have Ubuntu and am using Firefox browser.

Or can someone provide me with a toll-free support phone number that I can call?

Generally speaking, you can install Firefox plugins from websites in Ubuntu the same way you do in Windows, though plugins designed to work only with Windows will sometimes not work for Ubuntu. If you are unwilling to provide specific examples of websites and/or plugins that you are having trouble using, then there is no way for us to provide any further assistance. There is no toll-free hotline for gratis Ubuntu phone support; depending on your needs, you might consider paying for support (you can research this at http://www.canonical.com).

But if you can give us examples of websites and plugins you are having trouble using, we can very likely help you for free right here.