as i understand it, you should do this in two places;

you can make your server require encryption from everything connecting,a dnt he native client will handle it automatically:

SQL Server Configuration Manager and click properties for "SQL Native Client Configuration", if correct, you should be able to see two flags, one is "force client encryption", which you want to toggle to yes.

seperate from that, when you build an application with a connection string, one of the parameters is Encrypt=yes;

Driver={SQL Native Client};Server=myServerAddress;Database=myDataBase;Trusted_Connection=yes;Encrypt=yes;