formatting external harddisk

[Philippe Landau]

thanks Nano

>>>>found no GUI formatting tool (is there one ?)
>>>GParted
>>i installed it now, switched to sda,
>>created a disk label (default: dos),
>>clicked on "unallocated", new partition, fat32,
>>apply but get "Error while creating /dev/sda1"
> You have to make sure it's unmounted when trying to format a drive
> with gparted.
how can i unmount it ?

kind regards     philippe