In your database create a “content” table (call it what you like) with columns for id (name/number reference) and then each bit of data — title, subtitle, content, etc. User input (GET request?) should be sanity checked and then used to retrieve the relevant items as variables.
You can then develop a separate interface for adding articles.
For a more comprehensive look at a PHP design that does what you are describing, look at the source code for Kroc Camen’s site, camendesign.com.