Is an user manual enclosed with the ordered device?
Most Chinese manufacturers only include a Chinese quick start guide, but even renowned manufacturers such as Motorola or Apple do not provide complete manuals these days.
It is generally assumed that you explore the system yourself. With MIUI or Emotion UI it is very easy to find your way around, because both Android interfaces are quite self-explanatory. If you take a little more time with it, you will also find the little secret features.
Stock Android smartphones usually have a small guide during the first setup (software-based).