We have two options for printing certificates!
If you are seeking to print generic certificates stating that students have completed an Hour of Code, go to http://code.org/certificates.
If you are seeking to print certificates of completion for a specific course, the 'print certificates' button found in your teacher dashboard's list of sections will generate certificates for all students in that section (each of which you can remove individually if you'd like), stating the assigned course as completed.
Just click the down-facing arrow to the far right of each section to bring up an option for certificates:
We also have a few resources for blank certificates you can customize yourself: