@jcampos Good morning! It's actually really easy, all I did was put the xcp-ng ISO onto a USB, rebooted the server and booted from the USB. From there, it's just a case of selecting the option to upgrade XenServer 7.2 to XCP-ng 8.2. It really is that simple, probably more simple than anybody would imagine. There is XCP-ng documentation on the process as well - https://xcp-ng.org/docs/upgrade.html#upgrade-from-xenserver.
I would always recommend doing backups though before doing any upgrades etc. but in all honesty, from my experience, it was a very simple, quick and hassle free process.