Import HTML/CSS site to Wordpress

I created an custom website using html and css for a client. However, i want the client to update his website by himself, and what i’ve heard is that wordpress is the best and easy way to do it.
But what is the best way to import it? is there another way?

ps: essencialy, the client have to add images to the website

Hi, you can create a custom Wordpress theme which can have templates with your static code inside (and then replace the satic code with self-publishing custom fields. Example of templates: index.php, header.php, footer.php., about.php
If you are not familiar with creating a custom theme I advice to take a course on that matter. Now for self-publishing capabilities I advice you to use the following Wordpress plugin Advanced Custom Fields – WordPress plugin | WordPress.org
Which can be used to add an image custom field that can be added to a post type or page to name some of the available options, do note this is a lot to process if you are not familiar with Wordpress.