When you use cfdisk, it will show you the free space on the disk, assuming you haven't created partitions yet. If you have, highlight the large partition, and make it smaller.
Then select the free space and make another primary bootable partition, or make an extended partition. If you make an extended partition, select it, and make a bootable logical partition inside the extended partition (for another distro).
If you haven't made the swap parition yet, make the extended partition small enough to leave free space at the end, then select that to make the swap partition.
After you have done all the partitioning, select Write to write the partition as the last thing to do before exiting cfdisk.
Then reboot. It one of the few times in Linux you need to reboot after making changes.
Note: if you write the partition table after each partition is made, you may end up with inconsistencies, such as overlapping partitions (happened to me a couple of weeks ago).
Had to delete all, reboot, do it all over, and reboot again to get it right.