I am using fedora8. Now I have down loaded fierfox9. Please advise me how to install
 

how to install firefox9 in fedora8?

Since you have provided pretty much no useful information, i am going to take a guess... You cant.

Fedora 8, has been unsupported for 2+ years, Firefox 9, probably requires dependencies that are newer than you have.

Upgrade to a later version of Fedora (16 is the current), and try again.

you do not on fedora 8
fedora 8 can not even use fiefox 3
the last firefox update on 8 was " firefox-2.0.0.19-1.fc8.i386.rpm "
firefox 2 !!!

you are 8 versions of fedora out of date .