WordPress displays posts in reverse chronological order on the home page by default. So, to make something appear on the home page, you can just start adding posts.
The php files that determine the design are contained in the theme, and those files are located in
You can go to the Appearance > Editor section to modify theme files. The core content area is typically in the index.php or home.php file. See the documentation on WordPress Theme Development to learn more about the various theme files.
Make sure to backup before making changes!