<id="active"><a href="#">Item one</a></li>
<li><a href="#">Item two</a></li>
<li><a href="#">Item three</a></li>
<li><a href="#">Item four</a></li>
<li><a href="#">Item five</a></li>
Notice how ‘Item One’ has been given the id active, the style active contains the information to make that piece of the navigation higlighted. Basically, for each page, you would have to set the id of the bar to active and remove active from the other area. For instance, if you would like to switch to Page 2 and have it highlighted the code you would use is as follows:
<li><a href="#">Item one</a></li>
<li id="active"><a href="#">Item two</a></li>
<li><a href="#">Item three</a></li>
<li><a href="#">Item four</a></li>
<li><a href="#">Item five</a></li>
Notice how the first line no longer has the id=”active” and now the second line does. Now, if you mean, how can different pages in wordpress, such as ‘www.website.com/?page_id=2’, automatically highlight that button for that page, I don’t know how to do that, I tried. But possibly you coult look into the custom fields that wordpress allows. Check those out at https://codex.www.remarpro.com.
Hope it helps!