how to instal file js in theme Interface

Hello

I have some problem:
So I have website with installed theme Interface. On the main page you can see some map with areas. Idea is next: when you hover on some area on this map apply some styles – color background change and border.
So this styles are in js file. And I need set the path to the file – but I do not know how…
Before this I follow this way : wrote in header.php <script type=”text/javascript” src=”<?php bloginfo(‘wpurl’); ?>/wp-content/plugins/my-plugin/jquery.js”></script>
and this is worked. but now i really can’t understand how and where I should write way for my JS file.

So, i hope you understand me and can help!
Thanks in advance!
Best regards
Yulia