To pass to the next level, you must simply gain experience points.
There are multiple ways to achieve this:
Play an Episode Play a Replay of an Episode: The possible amount of experience points earned decreases with each replay for the first 10 replays, starting with the 11th replay, you cannot earn any experience points. Play a Mini-Game: Maximum of 20 experience points possible.. In Exploration: Points possible are random. Consume Experience Potions, you can purchase this at the Alchemy Shop in exchange for Gold Coins.
To access a mini-game or to explore, you must have a companion. Therefore, it is not possible to access these features at the beginning of your adventures on Eldarya.
You can follow your progression by viewing the number in the circle located to the right of your Guardian's profile picture.
Is it possible to change Guards?
It is possible to change guards during episode 2 in A New Era. You can either choose to stay in the same guard you were in during Eldarya: The Origins, or to take the test again and join another guard. If you don't like the result of the test, you can choose the guard you want to join.
To change your guard again, you will have to complete a Story Replay of episode 2 in A New Era.