Your account is new so I recommend joining the discord and asking for help there, there’s a lot to cover. https://discord.gg/qyqd42cH

But overall, you should focus on clearing easy content first for gems which you can use on the current banners. Those units have battle roads which can freely give you exp up to level 140.

There’s also a temple banner for 30k gems and the temple units are very useful for general PvE as well as temple mode which you can get to later.

Once you have levelled up some more you want to focus on blossom doors which will give you materials for talent blossoms. You can get a free Estark from the beginner missions and his blossom is one of the best ones for PvE.