To use cipher you simply pass the field you want to encrypt as the parameter, you can also specify a password which is used in the encryption, like so:

SET LIBRARY TO Cipher50.Fll

X = "This is a test"

Y = Encrypt(X,'Password')

Y should now contain the encrypted string, you will have to specify the same password in the decryption process, also this is case sensitive.

You could also look in the files section, as I know that a couple of encryption routines have been uploaded.