Does anyone know how to đăng tải các bức ảnh to change the user biểu tượng from the default little green man to actual pictures?

Go to your thông tin các nhân and click where it says "Upload photos";
Then, đăng tải the bức ảnh bạn want to have as your user biểu tượng (don't forget to mark the square that says "Make this image my user icon").
And that's it! :)

Hope it helped!