working at a job that doesnt train

i just did my first shift at wendys yesterday, which was a mess. my trainer was just so out of it and mumbled the whole time. im working front register. WTF DO I DO?? is there anywhere i cam practice the pos system? idk how to make any of the frostys, idk what my duties are, idk what im doing😭 .my trainer was just making me follow him throughout the day, not explaining shit. my next shift is on sunday opening shift, and they said im gonna be on my own. genuinely wtf do i do. idk. im going insane bc im just gonna look stupid and just stand there. how do i know what to do? they dont give like a checklist or anything, and ik that the tasks for closing shift (what i did today) are not the same as opening. pls someone help, tips or advice 🙏🏽🙏🏽 im begging yallpls! can u guys give me like a detailed rundown on what u do at work, or on a usual shift? working at front register btw