Help with first time connecting flight

Hi! This is the first time I am travelling alone and I'm newly adulting and inexperienced at this so please forgive my anxiety over figuring out how to navigate airports!! I have two connecting flights today but they are operated by qantas and hawaiian airlines (MEL --> SYD --> HNL). I've tried repeatedly to online check in but the websie & android apps just give me error codes. Should I be worried? Also do I collect my own baggage and then re-enter the airport?? I'm so sorry for my dumb questions I've never done this before. Any advice would be appreciated!