mining dirt is the hardest thing to do in terraria nad not many people know how to do it.
considering dirt is everywhere you will eventually need to mine this pesky ore.
steps to mining dirt:
1. kill all the bosses in terraria and get the best pickaxe you can
2. step carefully to a dirt block
3. select the best pickaxe you have (it must have LEGENDARY)
4. start mining and you should have dirt in your inventory
dirt can make the most OP things in terraria and defianetly is the most useful
if you have any more questions on how to mine dirt ask in the comments and I shall help you get the best pickaxe you can.