I do not have an easy answer for you, you will need to do additional research based on this response.
Crystal Reports is commercial software that allows report creation using templates integrated with external data sources that can include JDBC accessible databases to create finished reports. But PHP integration directly into that software is not well documented nor can the user customize the form. One approach is to use COM objects to load it, but your server must be Windows. Another is to use their XML-RPC web based API known as "Crystal Reports Web services" and nuSOAP to access it - but you still need to buy and install Crystal Reports, I believe, i.e. there is no public API.
None of this is easy, anyway so you should ask yourself if you really need to use a report tool like that. For example, PHP has wonderful PDF tools and there are many graphic libaries like JP Graphs for chart or certificate template creation.
Aside from a third party expensive reporting tool like Crystal Reports or similar and beyond the advice given, you might simply want to find a pic of a blank certificate but with the fancy grpahics (or a template in Word or whatever exported as HTML then extract the image) and simply use the GD library to overlay your text.