Hey there! As explained to you, you have to apply for Helper - but there are requirements that you need to meet before you're able to apply (e.g: you must be 13 years or older, have access to Discord, have 50 hours on the realm you're applying for, etc).
It's great to see your enthusiasm, but I would strongly suggest playing some more on the server before considering applying! it helps to get to know the server and the community before jumping straight into staffing, and making sure you know where to apply and that you know what is expected of you as a possible staff member.