I don't use any special plugins nor do I modify the back end. You can use WordPress as is. Here's an example of a site using WordPress as a CMS that I just launched last week: http://tinyurl.com/yksu4lt .
Have you ever looked at the dashboard of WP? If not, maybe you could sign up for a free wordpress.com account just to get your feet wet. Either that or you could install the default on your own server somewhere.
To make it act like a CMS, just go to Settings > Reading > and then select a "static" page to be your front page. Then select whichever page you want to hold your blog. Of course, these pages should be created first before you can set them in the Reading settings.
So, on the site that I linked above, the front page is set to "Welcome to .... " and the blog page is set to "Blog".
To edit or add static pages, you would go to Pages > Edit or Add New. These would be like the regular pages of a website.
To edit or add blog posts, you would go to Posts > Edit or Add New.