Subject: Endothermic process

Could you please give an "elementary" explanation of what an 
endothermic process is.  Remember, we are just grade 4/5/6 students.
What is the reason that salt is needed in snow to make ice-cream?
We know that the milk/sugar/etc. mixture freezes after snow and salt 
layers are put around the mixture.  We also know that the snow gets  
almost to cold to handle, but what is the scientific explanation for 
this?
 
We also know that salt is put on slippery icy surfaces to melt the 
ice.  How is this related to the same scientific explanation as when 
making ice-cream?

Re: Endothermic process