Hi,

On firefox, select Tools ->Add-ons->Get add-ons->search for firebug and click to install.

Regards,

Luis

Or just click the big red button on that page...click the "allow" bar that pops up at the top of Firefox....then wait 4 seconds to click "install". Finally you have to restart Firefox.

Are you having trouble because you are in a different browser? Chances are, if you can't figure out how to install firebug, it probably won't be of much use to you. For everyone else, it's wonderful.

Firefox is not good.
No is good enough.

Also, Chrome has a great set of developer tools that have debugging and such. I've switched to it lately. Seems to be very good.

And for those who wants some basic tips on how to use it, they can check my latest post.

There's also another great plugin for developers called (literally) Web Developer:
Web Developer

now a days, a new 3.6.3 under the FF, when you install firebug 1.5.3 always prompts a download error 278, tried several issues remain, and later on directly from third-party sites to install the next one, done!.

sometimes the latest Firebug is not tested with the latest Firefox browser update, probably wait a while to get things sorted .. else you can use IE -> Internet Developer Toolbar (should comes with IE 8, else has to download separate for IE 7) for temporary usage.