The wordpress page is index.php.
You need to install wordpress in a folder under your domain root. Something like Yourdomain.com/news would be perfect.
Then you can send people to the news page through a link in your HTML Home page.
But seriously, WordPress is a powerful CMS and more than qualified to be your homepage and news page.
In the back end of WordPress, you can create as many pages for your website as you need. Then, in the general settings, you can set one of your pages as the home page and set another one as your blog/news page.
If you are adept enough to make web pages with HTML and CSS, it wouldn't take long for you to install a theme that resembles your site and tweak it to your liking.
The look of WordPress pages are a combination of several files you can open and edit in the Appearance > Edit section of the admin console.
Here are the files that make up one of my current site themes:
404 Template (404.php)
Main Index Template (index.php)
Page Template (page.php)
Search Form (searchform.php)
Search Results (search.php)
Single Post (single.php)
Theme Functions (functions.php)
The Main Index Template (index.php) fires when a visitor reaches your WordPress site. It calls several other php files above to build your page.
Header.php constructs your header with your banner etc.
Sidebar.php builds your sidebar.
Page.php handles building the meat and potatoes -your main content area.
Footer.php constructs the footer.
All of this is done while obeying the relavant style.css file and the settings stored in your site's SQL database.
Open index.php to see what it's doing.
WordPress PHP files write the html for the page the user want's to see on the fly.