Craft a pick ax from a crafting table. Then craft a chest. Once you have those two thing crafted, just keep mining rocks. On the Windows 10 there is different types of rocks. You are looking for cobblestone. Just keep putting it in the chest, and you will eventually have enough.
I've contributed to making a world/walkthrough earning you all achievements really easy. You can check out the walkthrough on the following link. https://www.trueachievements.com/gam.../walkthrough/1
The achievements are grouped per update, although if you are somewhat familiar with the game, just hop into the world and do the achievements without the help of a text guide. Please let me know if you need any help.