The traditional way

• Login in the Joomla! back-end, usually at www.your-site.com/administrator/
• From the main menu, select "Installers > Components".
• There you will see the "Install new Component" form with a single field labeled "Package File" and the list of installed components.
• In the " Install new Component" press the "Browse..." button
• Now you can see a dialog box where you must search the compressed containing the component software.
  
  Important: Note that some components like Community Builder includes more than just the component in the compressed file that you can download form their site, so you must decompress the file locally finding other compressed files in it. Extract the compressed files but do NOT uncompress them.
• Once you have located the desired compressed file, double-click over it. This cause the dialog box to close and get you back to the Joomla! back-end screen, and the local path to the compressed file appears in the "Package File" field.
• Push the "Upload File & Install" and wait until the screen changes.
• If everything was OK, you will see a "Success" message as well as some text defined by the component's developer that usually contents some basic help, read it carefully and click over the "Continue" link at the bottom of the screen.
  Important: To ensure a proper installation, don't forget to click over the "Continue" link before you try to access the recently installed component.
• Now you can configure and use the component. Do not forget that some components require that you create a menu link so your users can access the component from the front-end.
  

Successfully installed but can't find it in component's menu?

Sometimes, when installing components from large compressed files, the component reports a successful install, but it did not complete the installation process, this is somehow related to script's maximum execution time defined at the server configuration and your internet connection speed.

If you fall in this situation, try to uninstall the component from the Joomla! back-end and continue with the alternate installation method, if the component is not available to uninstall, then continue with this procedure as if you got an error message while installing.

Got an error while installing?

There are several reasons why a component installation could be unsuccessful, the most of them are related to the server configuration, so don't get frustrated, take it easy and leave your hair on its place.

The first thing to do after a failed installation attempt is review your server files via FTP client and eliminate the all files already copied (if any) and all the folders already created.

The Joomla! components use to place theirs files in their own "private" folder, named something like com_component_name where component_name is usually associated directly with your component and usually there are at least two of this folders located at:

• components/com_component_name
• administrator/components/com_component_name
  

Alternate installation method

• Once you have manually removed all files copied by the failed installation attempt, you're ready to try it again, but this time we'll use this alternate method.
• Uncompress the component locally in your PC in a folder named anything you want, for this documentation we'll name it as com_component.
• Use an FTP client to upload the recently extracted files to administrator/components/com_installer/component/com_component
• Login into your Joomla! back-end
• Select "Installers > Components" from the main menu.
• Below the text field you used to install the compressed file you'll see other text field labeled "Install directory". This field is previously filled with an absolute path that usually just need to be completed with "/com_component".
• Verify that the absolute path points to where you uploaded the component's installation files
• Press the "Install" button that is located at the right side of the text field and wait until the install process finishes.
• If everything was OK, you will see a "Success" message as well as some text defined by the component's developer that usually contents some basic help, read it carefully and click over the "Continue" link at the bottom of the screen.
  Important: To ensure a proper installation, don't forget to click over the "Continue" link before you try to access the recently installed component.
• Now you can configure and use the component. Do not forget that some components require that you create a menu link so your users can access the component from the front-end.
• Use your FTP client to delete the installation files that you uploaded in administrator/components/com_installer/component/com_component

Do you still have error messages?

With this two installation methods you should be able to solve the most common component's installation errors and the next step will depend on what kind of error messages you are receiving.

• If the messages refers to other component using an specified folder, go back to delete previous installation attempt step and delete the files and folders listed there PLUS the ones generating the error. Since some components uses other folders in addition to com_component in the components and administrator/components folders, it's possible that you didn't delete them and they're causing some errors.
• If you're receiving messages about tables already exist in database, use your database administration software (usually phpMyAdmin) to delete them, uninstall the component if it's possible or manually delete component's files and try a new installation attempt.
• If at this point you can't get a Success message from your installation attempts, write down the error messages (a screen capture could be more helpful), and contact the software developer mentioning at least this information:

• On which version of Joomla! you're trying to install the component. 
• The version of the component you're trying to install.
• Your server's operating system (at least windows/linux)
• PHP version
• All the message errors you're receiving or attach the screen capture of this errors.