If you want to insert the gallery into Wordpress, please go to the Administration area of your website and then create a new Page. Using the WYSIWYG editor, switch to CODE mode and paste the code from the main HTML file. The rest of the files should be placed in the root of the website (eg. ../gallery). The paths need to be changed in the HTML file to point to that directory. Also, based on the width and height of your blog, adjust the settings in the HTML file so the gallery fits in the page.
If you want a simple approach, upload all the files into the gallery then create a custom ITEM in the navigation menu pointing to the /gallery folder and that's it. Every time a user clicks the link in the navigation menu, it will be transferred to the gallery.
Personally, I believe this approach is better because the gallery will be seen entirely without any modifications.