Deploying transparent data encryption
This article has a great step through exactly how to enable TDE.  This includes generating keys/certificates, everything.  When you turn TDE on, it will start encrypting in the background as well as when pages are accessed or flushed to disk.

Also, sidenote, TempDB also gets encrypted so if you have other DBs/SPs that aren't encrypted and use TempDB, there may be a slight performance hit when you lay data down in TempDB and pick it back up.  You're on 2016 so you still get native backup compression with TDE (hooray!)

http://joeysbasisblog.blogspot.com/2013/10/enable-or-disable-transparent-data.html