Download the installation program from any free download site.
We recommend the following link: http://www.mozilla.org/en-US/firefox/new/

After finishing the download, start the installation wizard by double-clicking the file.

Then on the startup screen, click “Next”, as the following image shows:

Select the preferred installation on the following screen, we recommend the default installation, after selecting the desired installation, click “Next” as the the following image shows:

The following screen is displayed showing the program installation location, we recommend installing it in the default folder, and then just click “Install”, as the following image shows:

After concluding the installation process, select the “Start Firefox now” option and after click “Conclude” as the following image shows:

Now your Mozilla Firefox is installed and ready for use.