Know everything about the FUTURE MARKET

I am newbie to stock market. I am having lot of queries about future market.
Example :
Cairns Ind ( Nse Fut 150.90 ) - Lot size 1250
1)Buy (1 lot) Fut Cairns of December Month @ 150.90 Rs
Approx. Paid = 150.90 *1250 = 188625

i want to know that how much i have to pay for the 1 lot of cairns india.

I heard about the margin money...!
What is that?

please help me out.
Thanks!