You can insert a button directly into a blog post, product page, or content page by using the Shortcodes feature built-into Ozcart. At the place where you want the button to appear you need to use the [button] and [/button] tags together like shown below:
[button]put your button content in here[/button]
The content for the button could be a link to another page, or an automatically generated link to a product using another shortcode. See the shortcodes article for a list of the available shortcodes that you can use, including ones to link to a product or category page.