I need to find a certificate on the computer that I can copy, make
changes and print to hand out

You don’t specify your operating system or what software you have so
this may not meet your needs but most users appear to be using
Microsoft products and I am answering the question on that basis. The
specific item you are looking for is usually known as a template, that
is, a generic form which you can modify to fit your needs by merely
keying in new text.

Most basic Windows installations include something called Microsoft
Works. There is a certificate creation wizard built into that
application. Look in Task Launcher, Cards & Crafts, then click on
Certificates for a wizard which will walk you through the creation of
many types of certificates.

You will also find Microsoft Publisher certificate templates available
for free download at the Microsoft site.
http://www.desktoppublishing.com/templ_mspub.html

Search terms

Google terms
microsoft download certificate template
://www.google.com/search?sourceid=navclient&q=microsoft+download+certificate+template

I hope this is what you were looking for.  If you aren’t using some
version of Windows then please ask for a clarification and I will post
links to other online software which should meet your needs. You can
also simply enter the name of your program in a Google search box,
along with the terms download certificate template and you will
probably get dozens of useful links.