Don't do .txt files. Don't be a pussy. This is a very easy project to start learning MySQL. Plus, there are tons of things you can do with a database other than search it for a text string.
1. If you store your news in a database then you all you have to do is store the date it was entered as one of the fields in the entries row. Then you can just selectively get the 10 most recent news post, or whatever.
2. There would be no manual movement of files. Archiving, etc would be automatic.
3. files are much harder to work with properly than a database.
4. A database would be much more effecient. Why use programming if you are going to castrate the concept. That's like buying car so you can store your gas in it. If you want to store your gas, get a gas can. If you are using a car, then fucking drive it.
This is a great tutorial to get started with PHP/MySQL:
http://www.sitepoint.com/article/228
So that you have a framework of what you need to do, I will diagram the process below. When you hit a question, ask. BTW, I'm not going to help you do this with txt files. That's just a waste of both of our time.
Use phpmyadmin or other db utility to create a table in your database. The table should have a prefix to distinguish it from any other projects in the same database (such as you found with phpbb). I would use ck_, but it is your choice. You will need a field for the text, id, and date. The table might look like this:
ck_news
=========
ck_news_id (int)
ck_news_post (text)
ck_news_date (varchar)
everything should be obvious, but make sure that when you are populating the ck_news_date field, that you use a unix timestamp
Put a bunch of crap in there to test it as well.
When you build the page that you want to have the news, it would be easiest to just create a news.php file and include it on your main page, rather than do the programming on the main page itself (btw, includes, and mulitple includes are no problem - include 100's if you want).
On news.php, connect to the database (see the tutorial above). Then you need to create a simple query like:
$result = mysql_query("SELECT * FROM ck_news ORDER BY ck_news_date DESC LIMIT 0,10");
maybe that should be 1,10... don't recall off the top of my head. You'll figure it out.
The result is nothing more than a mathematical place holder of the results found in your query. There is no data directly accessible from it. You need to create a loop to manually extract the rows from it.
Then you need to get the data from the query:
while( $row = mysql_fetch_array($result) )
{
echo("posted on: " . date("Y.m.d H:i", $row[ck_news_date]) . "<br><br>$row[post]");
}
Boom! done. If you want to see all of them, just don't specify a limit.
I gotta go, ask more questions as they come, or post if I wasn't clear. If you find me online (IM'ing) then I'll explain in excruciating detail what you are actually doing).