The exchangeserverpro.com site has the below excellent articles,
to create the certificate request:
http://exchangeserverpro.com/create-ssl-certificate-request-exchange-2013/
to compete the pending request:
http://exchangeserverpro.com/exchange-2013-complete-pending-certificate-request/
and to enable it:
http://exchangeserverpro.com/exchange-2013-assign-ssl-certificate-to-services/

Pantelis Apostolidis is a Cloud Solutions Architect at Microsoft and an ex Microsoft Azure MVP. For the last 15 years, Pantelis has been involved to major cloud projects in Greece and abroad, helping companies to adopt and deploy cloud technologies, driving business value. He is entitled to a lot of Microsoft Expert Certifications, demonstrating his proven experience in delivering high quality solutions. He is an author, blogger and he is acting as a spokesperson for conferences, workshops and webinars. He is also an active member of several communities as a moderator in azureheads.gr and autoexec.gr. Follow him on Twitter @papostolidis.