D&C 12

The Lord said to Joseph Knight, Sr., -

"...behold, I say unto you, keep my commandments, and seek to bring forth and establish the cause of Zion."  (Doctrine and Covenants | Section 12:6)

Adding -

"...I speak unto you, and also to all those who have desires to bring forth and establish this work..."  (Doctrine and Covenants | Section 12:7)

So this instruction to Brother Knight is to all who desire to serve.  This instruction is 1) keep the commandments, and 2) seek to bring forth and establish the cause of Zion.  In my mind, Zion is where people live according to the manner of the Celestial kingdom on earth.  The cause then is to become like.

What does it take to do this ?

"...no one can assist in this work except he shall be humble and full of love, having faith, hope, and charity, being temperate in all things, whatsoever shall be entrusted to his care."  (Doctrine and Covenants | Section 12:8)

In my mind, living is this manner is Zion.