Custom theme not showing

I’m new to WordPress and I’ve been following an online tutorial as I would like to build an existing website into WordPress. However, it seems I have fallen at the first hurdle. Even though I was following the tutorial to the letter, I’ve imported my theme but it will not show when I preview it. In fact nothing shows, just a blank white canvas.

I’ve got this far:
1 – created my style.css, index.php, header,php and footer.php files.

2 – referenced my css files in style.css like this:
@import url(‘css/bootstrap-image-gallery.min.css’);
@import url(‘css/bootstrap.css’);
@import url(‘css/bootstrap-theme.css’);
@import url(‘css/socialButtons.css’);
@import url(‘css/khCustom.css’);

3 – pasted the top part of the code from my index.html for the header.php file down to the opening container and from the closing container for the footer.php files.

4 – referenced the header and footer.php files in my index.php like this:
<?php get_header(); ?>

<?php get_footer(); ?>

The theme preview in WordPress is showing as blank but I thought this was just a preview thing, as the webpage is completely blank too. But the tutorial said the headers and footers should be showing.

I’ve tried altering the links to the css files by putting a / in front, without a slash, ../, …/, … on it’s own. Any ideas a to what am I doing wrong?

Thanks!