Minecraft classic server?

Hey guys im just asking about minecraft, i didnt buy the game but i got a downloaded version. I wanted to know ive seen mega builds on youtube of people they have flat ground with blocks that have unlimated supply and they press a button and different coloured blocks come up.You can also break blocks with 1 hit. i think it was called a classic server but i dont know how to do it. if anyone could explain a word for word tut on how to get classic map onto my minecraft it would be great thanks