[Help required] for facebook

I have seen replies from facebook fanpage on other fanpage

how do fanpage post commnet or update..

If you mean how do pages post on other pages-
You have to be an admin of a page.
You go to the admin panel for the page.
View the page.
Then click "use facebook as [page name]."
Then, you can use your page as if it's its own profile!
It's a VERY interesting and useful feature indeed.
ENJOY.

thx i need to bbe admin f the page I want to post from

indeed this is very interesting feature if we can post message on others page.

you made my day