If you are just starting to play Terraria, I recommend focusing on resource collection and a simple shelter to get the night creatures through. Drill deep because underground are valuable ores and life crystals that boost your HP. Crafting bases like Furnace and Anvil are also necessary.
I didn't originally know, but you learn. It's all about experimenting and trying out weapons and armor. Bosses are tough, but the payoff is great.
