It is very hard to give step-by-step explanations to an elaborate module such as is used for e-mail communication, especially if microflows are unknown.
I recommend you to follow the Mendix learning paths. Here you will learn all the essentials;
Edit: I saw that you already have the Rapid Developer Certificate, so the concept of Microflows should not be new to you. Could you give a bit more detail about what you tried and what you would like to achieve?