How to disable the warning '... was downloaded from the Internet...'

Hi,

I download 'Firefox' to my Mac. But everything I start it, I get an warning:

"“Firefox” is an application which was downloaded from the Internet. Are you sure you want to open it?"

Can you please tell me how can I eliminate it?

Thank you.

First off you have to install fire fox
You would have downloaded the dmg file > double click to open > Open Finder > Drag the Firefox app to applications in finder. You can then trash the dmg if you don't want to keep it.
The warning only shows up the first time you open a downloaded app = security.

Notes:
The trash is called trash because it isn't a recycle bin.
You cannot cut in Finder.
Files do not Merge they are replaced.
Open apps show a light under them in the Dock. The Red button doesn't close multi window apps, they stay open for quick reuse.
command q to quit selected app.

Please check out some of Apple's support sites:
Apple - Support - Switch 101
Apple - Support - Mac 101 - All Work and Play
S.

Thanks. But I think I did install it.
I click the 'firefox' icon in the Applications folder.
Do i need to 'uninstall' firefox and try again? If yes, how can I do that?

Sorry. I am new the Mac environment.
Thank you for your help.

Are you sure you didn't just drag the DMG to the applications folder? When you open it, does it pop open a new folder with the Firefox icon inside? Is there an icon that looks like a disk on your desktop when you open it? If so, you need to drag the icon from the disk image into your Applications folder, then eject and delete the image.

BTW, uninstalling on the Mac is simply dragging the application to the trash. Empty the trash and it's gone.

OK, sorry, something is wrong, the security message shouldn't keep coming up every time you open Firefox. Clicking OK in the message should make it go away for good. If you 'windows clicked' the red button it will keep coming back.

Next time it comes up click the OK button and once it has gone restart your Mac > under the Apple on the menu bar top left. A restart settles new apps in and often sorts out strange behaviour.

Any application that was dragged and dropped to install (like Firefox) is just dragged out of the application folder to the trash to uninstall. Apps that have an installer usually have an uninstaller in the dmg file so keep it safe in a folder.