mount and umount ntfs

The kernel should be configured to write ntfs, or finally you can only read it. Mount a ntfs:

$ fdisk -l
Device Boot Start End Blocks Id System
/dev/sdb1 1 3569 28667961 7 HPFS/NTFS
$ mount -t ntfs /dev/sdb1 /mnt/point -o rw

For FAT:

$ mount -t vfat /dev/sdb1 /mnt/point -o rw

Check rw:

$ grep /dev/sdb1 /proc/mounts

If the line contains 'ro', mount cheated you: there is no ntfs write support in your kernel. You need to rebuild the driver.
Unmount a mounted point:

$ umount /mnt/point