-a- 64GB card formated exFAT is useless ( for NOOBS )
https://www.raspberrypi.org/documentati ... matting.md
-b- installed RASPBIAN anyhow would mean you burned a RASPBIAN image ( ? by etcher? win32diskimager?)
so step -a- formatting not needed.
missing info what file (full name) you downloaded and installed how?
-c- in case that burning RASPBIAN gave you a running system
you should check from there the actual partition layout
( and not from a windows PC where you only see one ( the first 68MB partition )
use the terminal commands
df -Th
and
lsblk
and show the results here.
-d- for working ( and learning linux... ) you should use RASPBIAN ( better burned to a other 8GB SD card )
for download burn LibreELEC
https://www.raspberrypi.org/downloads/
-e- if you want both as a multiboot SD card go back to the formatting point,
do it correctly for 64GB cards ( not exFAT )
and download / unzip/ copy the files from
NOOBS full
NOOBS lite
PINN lite
and ( with internet connection ) download install both OS via NOOBS menu.
-f- to the question:
Create new partition in a 64Gb SD
you could do by using RASPBIAN...
install "gparted"
and resize / create ... partitions,
but if you asked this regarding to install openELEC additionally to the already installed RASPBIAN
on that card, sorry, not work that way. ( see -e- for multiboot )