You're talking about the shopping cart sidebox, right?
Two ways to do this...
Both are edits of the following file:
includes/templates/template_default/sideboxes/tpl_shopping_cart.php
FTP a copy of this file to your local machine.
Open it for editing, with a good PLAIN TEXT EDITOR, such as Crimson Editor.
Right at the bottom of the file, the following appears:
PHP Code:
}
$content .= '</div>';
?>
-------------------------------------------------------------
You can either HARD CODE (the untidy method) the button link as follows
PHP Code:
}
$content .= '</div>';
$content .= '<div id="checkoutButton"><a href="https://www.yourwebsite.com/index.php?main_page=checkout_shipping"><img src="includes/templates/your_template/buttons/english/button_checkout.gif" alt="Checkout" title=" Checkout " width="114" height="20" /></a></center></div>';
?>
NB: make sure you put in your website URL and apply any other custom stuff like width and height settings for your button image.
-----------------------------------------------------
Or use the tidy method (recommended):
PHP Code:
}
$content .= '</div>';
$content .= '<div class="checkoutButton"><a href="' . zen_href_link(FILENAME_CHECKOUT_SHIPPING, '', 'SSL') . '">' . zen_image_button(BUTTON_IMAGE_CHECKOUT, BUTTON_CHECKOUT_ALT) . '</a></div>';
?>
SAVE the file on your local drive.
On your remote server, navigate to:
includes/templates/YOUR_TEMPLATE/sideboxes/
and then FTP the edited file to that folder. If there is no folder called "sideboxes" in your template folder, create it.
NOTE: I have given this its own style ID (checkoutButton) so I can give it a style later if I like.