Need help develop my website

hello

I have a website made in codeigniter made by a freelancer, www.aachange.com I need to develope the site more and the first thing is to implate a new button (menu) articles so I can write content on the site. I need a editor, cms so I easy can publish articles, make links to other articles. a easy for me to use editor.on the page should be under recent articles, "read more" yes like a normal blog page.
the site is php,html, ccs, I have local the ftp netbeans that you change in the site, and myphp in ISP.
you can email me if some one can do the job , and how much it will coast. allso how long time you need.
[email protected]

regards
mauritz