How to actually do death contemplation? How to do death contemplation ?    it seems i really dont care about dying that much   

how long can i do it ?  is there a formal technique to do it ? cause just thinking about it dosnt seem to have no effect at all  

i do seem to care about others who die though but not on myself  - and even on others i care much more about them being ill and suffer than them dying 

so any tips you have to add to make this more effective would be great  

and just to make it clear  : i want to do this to get a sense of urgency so i will meditate more so i will get chanda
i do seem to care about others who die though but not on myself


But that's the whole point. So if you already don't mind dying (that's how i understand your statement), then maybe you're an arahant?
I of course am not familiar with your background, but whether you mind or not can be found out in the life and death situation, when contingency of dying is very real.  Good health and safe environment are not the conditions to help to realize one's own mortality. An event which has a potential of causing a profound shift in one's attitude towards death is a death of a close relative, and especially a sudden and unexpected one, because it hits very close to home and with great impact due to suddenness.

Contemplation of death for development of samvega is described in Maranasati suttas 1 &amp; 2
http://www.accesstoinsight.org/tipitaka/an/an06/an06.019.than.html
http://www.accesstoinsight.org/tipitaka/an/an06/an06.020.than.html 

And here's how actual practice of perception of death is described in a Gandhari Samyukta Agama Sanna sutra (Andrew Glass, Mark Allon, 'Four Gāndhārī Saṃyuktāgama Sūtras: Senior Kharoṣṭhī Fragment 5')


  What is the concentration connected with the perception of death? In
  regard to this, a monk who is at the root of a tree, or in an empty
  house, or in an open space… thinks “I will die, I will not live long,
  I will perish, I will die, I will disappear. It is the undistracted
  one-pointedness of mind of a person so positioned, which is called
  “the concentration connected with the perception of death.