Enabling encryption on your macs harddrive is easy.

goto system preferences > security and privacy > filevault

click the padlock in the bottom left hand corner
type your password
click ‘turn filevault on’

you will then get a recovery key.
you can write this down, print it, email it, whatever you want.
note that if you want to you can send the key to apple and if you forget your password you can phone them and recover your mac.