Flowable Subprocess

Hi everyone,
This post is purely for UI side (flowable-modeler).I am trying to work with flowable subprocess, on UI , I am creating a process with task A , a subprocess and task B. But I am not able to attach the task 1 to subprocess. I have following doubts:

  1. How can we work with subprocesses?
  2. How will subprocess get attached to task
  3. Is it so that Subprocesse’s tasks need to be completed to move forward from subprocess to task B .
  4. How to create tasks inside subprocess on UI

Could anyone help. Thanks in advance