sign a key to the key ring

[Jomy Vellian]

Hi,

	Could you please tell me what command I should use to sign a key on
my key ring.
	I am using gpg 1.0.6 in solaris 8

	example:
	vftp# gpg .................

When I decrypt a file I am getting following WARNING----
 
Could not find a valid trust path to the key.  Let's see whether we
can assign some missing owner trust values.
No path leading to one of our keys found.
gpg: WARNING: This key is not certified with a trusted signature!

thanks,
jomy..