The first thing to do with Minecraft is to decide what you want out of it. Do you want to play on creative mode – able to place any blocks without having to work for them, and thereby building impressive edifices? Do you want to play with friends on their multiplayer servers? Do you want to collect lots of cute animals and tend them in cosy pens? Do you want to have a realistic immersive survival experience, with danger around every corner and having to battle to stay alive?
Depending on which this is, you will want to install different versions of Minecraft and different mods.