It,s freeware
Firefox 4.0 Beta 11 is also open source. This browser sets the pace with dozens of new features to deliver a faster, customizable and more secure Web browsing experience for all user.
For Windows OS.
- By the click the following link Firefox 4.0 Beta 11
- You will go to download page
- If you have finished doownload this, you will get a file with size about 11.32 Mb
- Go to your download directory
- Dobble click this exe file to run it