I am not sure of a direct way to implement a HTML page into a WordPress theme, but if you have made
footer files for your website, then all you need to do is convert them to make them WordPress compatible.
You should refer to the codex.
You can also go for any of the WordPress frameworks listed here.
A WordPress theme is easy to understand if you know basic PHP. It has a set of files like
- header.php // header file
- footer.php // footer file
- index.php // the index file
- page.php // for your WP pages
- single.php // for your WP posts
- and some other files
Go through the codex and it shouldn’t take long to get the hang of it.