Magic Letter?

I’ve been following the program for about 10 days now and some of the exercises has already helped a lot, however in one of the exercises “how to wright that magic letter” it’s requested that we write a letter to our ex and I wanted to know when is the perfect time to send the letter, doesn’t that go against the no contact rule? Please help, I’m so confused. Also am I allowed to like his pictures on social media or does that also go against the no contact rule?