raspberry 3B+ change apt sources, install VNC, install python opencv

Change apt sources:

    1  sudo raspi-config 

    2  sudo apt-get install vim
    3  sudo vim /etc/apt/sources.list
    4  sudo apt-get update

Install VNC

   5  ifconfig

   6  sudo apt-get install tightvncserver

Install python opencv
   7  sudo pip3 install opencv-python
   8  sudo apt-get install libatlas-base-dev 
   9  sudo apt-get install libjasper-dev
 10  sudo apt-get install libqtgui4
 11  sudo apt-get install libqttest4-perl