I am having an issue with a macro within a workbook I am sending out to other
people. I have no issue running the macro, but when someone tries to open,
they get the error "Macros are disabled because the security level is too
High and digitally signed Trused Certificate is not attached to the Macros.
Request the macros be signed by the author using a certificate issued by a
Certificate Authority."

How do I get a signature issued by a certificate authority?