Need help with buying a labrador please :d?

Well i want to get a labrador and it is such a BEAUTIFUL dog. Adapts well, loyal, and friendly. I want to buy one from the north melbourne lost dogs home :) there is one that is 1 year old , tempermants beautiful, clean, microchipped, and all the needle and stuffs up to date. Me and my parents were at my cousins house and they have a labrador, yellow ( same as the one at the LDH.) MY PARENTS LOVED IT ;D they said its a beautiful dog. i just need them to get our family one :D i just have a couple of questions... i have a large backyard. its going to live at the backyard, it will have a good place to rest, (a nice shed etc. ) i dont know which food to give it though, my cousin feeds it anything, dry,yoghurt , cheese, should i do the same? andalso what do i ask the people at the lost dogs home to buy it? i beleive that we should ADOPT NOT BUY :D i really lovee this doggy, just how am i meant to tel my parents?