How do you make filesystems in mac OSX

You can use Disk Utility (diskutil from command-line).

For example:

diskutil eraseDisk JHFS+ VolumeName /dev/disk2

Refer to the manual page.

On BSD-derived Unix systems, newfs is more commonly used than mkfs.

Under Mac OS X, you would use newfs_type as the command, where type is one of hfs, msdos, exfat or udf. There are man pages for all of these. As the other answer mentions, you can use diskutil to create filestems but by using the newfs variants you can set specific filesystem parameters unavailable via diskutil.