You have completed the first mission.

Kill a skeleton with an arrow from more than 50 meters.

Acquire 30 Emeralds by trading with villagers or mining.

Trade for the best possible price.

Swim in lava while having the Fire Resistance effect.

Use a saddle to ride a pig, then have the pig get hurt from fall damage while riding it.

Construct a Dispenser.

Craft and place a Flower Pot.

Kill a creeper with arrows.

Find an underwater ruin.

Discover 17 of 40 biomes.

Construct a Nether Portal.

Kill a mob next to a catalyst