how to add custom class to link?

Hi

Features say
'Advance settings for content area and pager area selector. If default html
markup override using the theme tpls.'

Im unsure what this means.

I am trying to theme the show more button but it does accept html.

I then tried to create my own html button and under 'Pager jquery selector
jQuery selector for the pager, relative to the view container. Use when you override the pager markup. Default is ".pager-show-more".'
put the selector for that button but nothing happened.

I then tried to copy the template to my theme folder and change the html there but it does not get loaded.

How can I customise the link?

Thanks