Hi Kemalettin,
first of all do you have a database for the news ??? If so there are a lot of GNU Licensed Newssystems on the market... I recently tried some of them but came to the conclusion, that I have to write my own ... that doesn't mean that they are not good, some of them feature a hell of functions ... For a (big) list of free Newssystems visit http://php.resourceindex.com/Complete_Scripts/News_Posting/ (The PHP ResourceIndex should always be your first look, if you want to find some readytogo PHP Scripts ...) Some of the systems I tried and found good:
PHPNuke (http://phpnuke.org): Its sort of the big good old PHP Newssystem, lots of features, very stable, but I found it a bit to uneasy to customize ... I've also got a tool to customize it (can't remember the URL, but if you want it, mail me).
PHPWebLog(http://phpweblog.org): This Newssystem I personally found best, it uses Templates, has a lot of usefull features (not as many as PHPNuke though) and its at least a bit documented (thats the worst about OpenSource... the code is nearly always undocumented <-- suckz like hell!!!)... Well there are so many more Newssystems, Geeklog for example ...
Anyway if you wan't to look for a Newssystem, don't get fooled up by the version number (I did it a while) some people give their first release the version number 1.05 (you think you have a stable system, but instead you play betatester), while others release the 10th stable version and call it 0.42 (e.g. PHPWeblog) So always have a look at the readme or the changelog file and see how many releases they've got ... To set up one of these newssystems never took me more than half an hour ... so you can test all that sound intresting ...
Well if you wan't to write your own Newssystem, it depends on what you want, but if you want a lot of features try to look what you can copy from other systems, because it is still a lot of work ...
hope that helps a bit :-)
cya Rob