not sure how linpus works but if it has a package manager that would be the ideal way to install/ upgrade it.
as far as i remember, firefox just needs to be extracted to run.
open a temrminal and type in something like:
tar -xvzf firefox.tar.gz
i'm not sure of the specifics so please repost and display the contents of that directory if you cant figure it out.
p.s.: i also have the revo 3610...