how do i determine which post will be in the FRONT PAGE

How do i determine which post will be in the front page "for ever"?
and i want just 1 post.

i mean when i publish a new post, i dont want it to be in the front page.

Try this...

query_posts('meta_key=priority&orderby=meta_value&order=ASC'); - then assign the post a priority of 1; all other posts get 5 or higher.

An easier way might be to just edit the post date of the one you want to keep first to something newer than the others.

HTH