How do I set permissions on a samba connection?

[Bob]

I have an existing system which contains a LAN connected disk drive.  I have
added a new computer on which I installed Ubuntu (this is my first linux
experience).  From the Ubuntu computer I can read the files on the samba
connected drive but I can not write to those files.  I have tried to change the
permissions but can not locate where the drive is mounted.  So my question is
how do I change the permissions?

-- 
Robert Blair