signing non default key

[Yard, John]

Forgive the newbie question:

I want to sign a key , I use

/opt/freeware/gnupg1.4.10/bin/gpg --edit-key Yard2004_UCLA

I enter 

Commnad > sign

     Yard2004_UCLA

Are you sure that you want to sign this key with your
key "John Yard (aix admin) <jyard at ais.ucla.edu>" (78B3C4BA)

Really sign? (y/N)

This issue is , I need to sign this key with another key ,
How can this be done / what is the syntax for this ?

JYard
UCLA