To generate a certificate, go to Certificate > Generate Certificate then select Class, Section, and Certificate and then click on the Search button. The list of the student will be shown below the page.
Now select student to generate a certificate and click on Generate button present on the right side in the student list, at the click of this button certificate will be open.
Note - Do not print the certificate directly, here select the Destination (save as pdf) and save the pdf file and then print the certificate using this pdf file.