IF that was too confusing, just read the help file on rufus or watch a video on youtube. anyhow always read or watch what u want to know and you will learn.

btw, u probably need Windows computer to run Rufus.

download rufus, download the .dmg that you want to have rufus write to your usb drive, plug in the usb drive, open rufus after installing it, once open select the drive that you want the program to be installed on (your usb drive), select the file that you want written to the usb drive (the program you downlaoded from the address from the file that you downloaded from the OP , the first thead on this topic), u shouldnt need to change any thing else on the program just run it to create the bootable usb drive. restart the computer...