Which slider is it? Does it insert as a shortcode, as a PHP template, or as a widget? If you post a link to the plugin page, I can take a look.
I am using a plugin called Meta Slider on two of my Montezuma sites: Lady Eagles Basketball and Venice Hongwanji Buddhist Temple. The second site actually has two sliders that can be seen on the home page, one in the header and the other in the main content area.
Meta Slider supports all three methods mentioned above: widget, PHP code, and shortcode. The widget is the easiest to implement. All you do is define a new widget area where you want the slider to appear. For example, if you want the slider to appear in the header, you edit the header.php sub template (Appearance > Montezuma Options > Sub Templates > header.php) and add a call to the function dynamic_sidebar to define your widget area:
<div id="colWidgetHeader" class="col12">
<?php dynamic_sidebar( 'Widget Area Header' ); ?>
Then you go to Appearance > Widgets and drag a slider widget into the new area.
If you want it to appear beneath the header, in the main content area of your home page, then what you will edit will depend on whether you have the default blog page as your home page or a static (non-blog) page as your home page. If you have a blog page as your home page, then you would edit the index.php main template using the same technique as above (Appearance > Montezuma Options > Main Templates > index.php. If you have a static page as your home page, then you would make a copy of the page.php Main Template and call it front-page.php, then create a widget area as above.