The installation of the program by the built-in most modern Linux distributions package Manager is the easiest way for a novice Linux user. To switch to automatic installation of applications, it is sufficient to invoke the corresponding menu item in the graphic shell of the system. For example, in Ubuntu, click on the menu icon the top toolbar and click the "app Center". For distributions that have pre-installed is KDE, the desired program can be found in section KPackage.
At the top of the new window you will see a field to enter a search query. Using the keyboard enter the word Firefox and press Enter. Wait for the search results and select the appropriate option from the suggested list. Click "Install". After the procedure you will see a corresponding notification and will be able to launch a browser via the applications menu under "Internet".
For Ubuntu users there is also the option to install the browser using the command line. Start the Terminal application by pressing Ctrl and T on the keyboard. In the screen that appears, enter the following command:

sudo apt-get install firefox
Wait for setup to complete. If necessary, enter the administrator password to complete the installation. Once the Terminal finishes carrying out the necessary operations, close the window and go to menu "Internet" by clicking on the system icon of the top toolbar.
For manual installation download from the official Mozilla website the application package in the TAR format.BZ2. Call the program "Terminal" or "Command prompt" (depending on the version of the distribution and the used graphical environment). At the prompt, enter the query:

cd ~
To extract the contents of the archive use the command:

tar xjf firefox-version.tar.bz2

"Firefox-version" matches the name of the file you downloaded. To know the exact title of the document, type ls and find the appropriate archive. Then to run the program, use the command ~/firefox/firefox.
To carry out start browser without invoking terminal, right click on the desktop and select "Create" - "New file". Name the document, Firefox, open it by double-clicking the left mouse button. Enter ~/firefox/firefox, then click on "File" - "Save" (File – Save). Right click and invoke "Properties". Check the box next to allow run in terminal and click OK. A shortcut to automatically launch the browser created.