Years of bug writing experience has been distilled for your reading pleasure into the Bug Writing Guidelines. While some of the advice is Mozilla-specific, the basic principles of reporting Reproducible, Specific bugs, isolating the Product you are using, the Version of the Product, the Component which failed, the Hardware Platform, and Operating System you were using at the time of the failure go a long way toward ensuring accurate, responsible fixes for the bug that bit you.
The procedure for filing a bug is as follows:
Click the "New" link available in the footer of pages, or the "Enter a new bug report" link displayed on the home page of the Bugzilla installation.
If you want to file a test bug to see how Bugzilla works, you can do it on one of our test installations on Landfill.
You first have to select the product in which you found a bug.
You now see a form where you can specify the component (part of the product which is affected by the bug you discovered; if you have no idea, just select "General" if such a component exists), the version of the program you were using, the Operating System and platform your program is running on and the severity of the bug (if the bug you found crashes the program, it's probably a major or a critical bug; if it's a typo somewhere, that's something pretty minor; if it's something you would like to see implemented, then that's an enhancement).
You now have to give a short but descriptive summary of the bug you found. "My program is crashing all the time" is a very poor summary and doesn't help developers at all. Try something more meaningful or your bug will probably be ignored due to a lack of precision. The next step is to give a very detailed list of steps to reproduce the problem you encountered. Try to limit these steps to a minimum set required to reproduce the problem. This will make the life of developers easier, and the probability that they consider your bug in a reasonable timeframe will be much higher.
Try to make sure that everything in the summary is also in the first comment. Summaries are often updated and this will ensure your original information is easily accessible.
As you file the bug, you can also attach a document (testcase, patch, or screenshot of the problem).
Depending on the Bugzilla installation you are using and the product in which you are filing the bug, you can also request developers to consider your bug in different ways (such as requesting review for the patch you just attached, requesting your bug to block the next release of the product, and many other product specific requests).
Now is a good time to read your bug report again. Remove all misspellings, otherwise your bug may not be found by developers running queries for some specific words, and so your bug would not get any attention. Also make sure you didn't forget any important information developers should know in order to reproduce the problem, and make sure your description of the problem is explicit and clear enough. When you think your bug report is ready to go, the last step is to click the "Commit" button to add your report into the database.
You do not need to put "any" or similar strings in the URL field. If there is no specific URL associated with the bug, leave this field blank.
If you feel a bug you filed was incorrectly marked as a DUPLICATE of another, please question it in your bug, not the bug it was duped to. Feel free to CC the person who duped it if they are not already CCed.
Starting with version 2.20, Bugzilla has a feature that allows you to clone an existing bug. The newly created bug will inherit most settings from the old bug. This allows you to track more easily similar concerns in a new bug. To use this, go to the bug that you want to clone, then click the "Clone This Bug" link on the bug page. This will take you to the "Enter Bug" page that is filled with the values that the old bug has. You can change those values and/or texts if needed.