Like all software there will be times when you use CiviCRM when things don't work the way you expect them to.
A good first step is to search the forums (http://forum.civicrm.org) for similar problems and follow advice given there. If your problem hasn't been addressed, posting to the forum is probably the right thing to do.
Before posting its a good idea to look on the forum for good posting guidelines and spend a bit of time writing your post. Make sure you are detailed and specific about what software you are using (i.e. the version of CiviCRM, which CMS platform and its version, and which browser and its version), what you are trying to do and how you are trying to do it. For example letting people know the url you are using (with any confidential details removed) may cause them to realise that you are configuring the wrong page. Unclear posts are less likely to get good replies.
If you are using an older version and the problem you are experiencing is a bug that has been fixed in the lastest release, be prepared for the answer "that it is time to upgrade to the latest version." Although the CiviCRM community tries to be as helpful as possible, and we recognize that upgrading puts a burden on your organisation, it is difficult to support multiple versions simultaneously.
Check the following possible sources of problems before you report something on a forum. You can save yourself and a lot of people trouble by isolating the problem. CiviCRM forums try to be friendly and don't criticise you for misjudging a problem, but you'll certainly get more help and resolve problems faster by doing some checking of your own first.
Recreating your bug on one of the demo sites (http://demo.civicrm.org and select the demo site that matches your CiviCRM version) helps determine whether your problem is a result of a bug in the source code, or as a result of changes on your site. If you can show us that the code on the demo site turns up your bug, it's very likely that the CiviCRM source code is the problem, and your demonstration will help us find and fix it.
Still, no demo site can cover all possibilities. Issues involving email output or payment processing cannot be recreated on the demo sites. So even if you can't reproduce your bug there, it might still be a bug in CiviCRM. It is, however, probably triggered by your server setup or other customisations.
Write to the forum and explain the problem you are experiencing. If the bug was reproduced on the demo site, describe exactly what you did there, and copy the demo site's URLs to document the steps you used. If not, include as much information about your server setup as you feasibly can. Configuration files from the web server, CMS, and CiviCRM will be valuable, but be careful to not including sensitive information such as your database log-in.
The best bug reports give lots of background and context. Don't forget that the way you are using CiviCRM is most likely very specific to your organisation. The more background you can give on the bug, the better.
The best bug reports clearly state:
The amount of time taken for the bug to be fixed depends on the severity and complexity of the bug. It could be as quick as the same day, but it could take much longer.
To get bug fixes, the easiest way is just to download and install the latest revision of CiviCRM. Downloading bug fixes between releases and fixing, called patching, your existing software is possible. If you have technical abilities, then refer to the CiviCRM Developer's Guide for instructions on applying a patch, otherwise, seek out technical assistance to provide tests and a patch for the issue.