LÖVE

Hi
I have problems with contacts in physics
I have an
object ={}
object.ball={}
object.ground={}

and i am trying to make love.graphics.print (touch,10,10)
beginContact(a, b, coll) <--- what do i need to put here?
in order for the touch to appears the ball its at 100,100 x,y
and the ground its 0, 400

Now i know it's a function but what do i put there i tried the wiki but it didn't work for me? the ball bounce perfect etc..
but once it touches nothing appears i know i am missing something but what it is??????

-snip-

Okay i do get that its from wiki but what is this means? also how can i use it for other actions? for example if ball touch the ground and let see another block appears ?
do i need variables? inside the begin and end functions? and use it under love.draw()?

is there more info about physics?any links??