RICHARD - I have heard the statement of Tenets thou shalt not speak. Can you explain what that means?

JOEL - This comes from the following scripture:

"And of tenets thou shalt not talk, but thou shalt declare repentance and faith on the Savior, and remission of sins by baptism, and by fire, yea, even the Holy Ghost." (D&C 19: 31)

In this scripture the Lord was instructing Martin Harris to not preach all the teachings and beliefs of the Church to the world, but to concentrate more on the basic doctrines of repentence, faith, baptism, and the Holy Ghost.
This was a personal revelation to Martin Harris who was about to preach to people unfamiliar with the Gospel of Christ. Earlier in that section the Lord explained why He did not want Martin to talk about things other than what He specified:

"And I command you that you preach naught but repentance, and show not these things unto the world until it is wisdom in me.
For they cannot bear meat now, but milk they must receive; wherefore, they must not know these things, lest they perish." (D&C 19:21-22)

God knew that the particular people that Martin was going to talk to would not be ready for more advanced gospel concepts(meat), until they understood the basics(milk) first.
The Apostle Paul gave a similar reason for not telling people everything about the Gospel all at once:

"I have fed you with milk, and not with meat: for hitherto ye were not able to bear it, neither yet now are ye able." (1 Cor. 3: 2, See also Heb. 5:12)