I did a full breakdown a while back in another thread. It is listed below.
Enchantments
are always played facedown, and remain hidden from your opponent until you choose to reveal them. You can decide that you would like to reveal the enchantment so that it has an effect on the game right away. You declare that you are is revealing it, flip it face up, and pays the reveal cost
When Can You Reveal?
You can reveal an enchantment immediately after any action or event in the game:
• At the end of any Phase of the game round.
• Immediately after a creature is activated, before it chooses its actions for the turn
• Immediately after a creature completes its move action, but before it takes a quick action.
• At the end of any of the eight steps of an attack or three steps of casting a spell.
• You can reveal an enchantment immediately after it is cast, right after the Resolve Spell Step. When an enchantment is “resolved” it is placed face down as a hidden enchantment. Then, immediately after it has resolved, you may choose to reveal it at the end of that Step.
• You cannot interrupt an event to reveal an enchantment.