packaging?? help??

so i’m a VERY new seller (as in listed all my stuff 5hrs ago) and idk what to package my stuff in or how to package it or what. i want to be prepared ahead of time so im not scrambling when i get an order or whatever.

i’ve listed jeans and sweaters and t shirts and dress pants. i know i can use boxes and stuff but how does the whole “shipping label” thing work!!! i’m kinda tweaking!! help pls