I guess someone told you that God did not reveal much about the Messiah in the Old Testament.  What I can say for sure is that you did not learn this from the Old Testament itself.  We learn a very great deal about the Messiah from both the prophecies about him, and even more so, from the types, prefigures and foreshadows about him.  Whoever told you that the OT prophets did not tell their generations in detail about the Messiah has it all wrong.  From the Old Testament we know:

Where Messiah will be born  Micah 5:2

Where Messiah would come from Isaiah 9:1-6

How Messiah would die Psalm 22::16

That the Messiah would be lifted up on a wooden pole to save us from our sins  Numbers 21:4-9

That the Messiah would be wounded, and, ultimately killed for our sins Isaiah 53

That Messiah would be a king who conquers, but who comes in peace Zech 9:9

That Messiah would be betrayed for the people for 30 pieces of silver Zech 11:12-14

That Messiah would come to Jerusalem would be anointed as king and savior in Jerusalem Daniel 9:23-24

That Messiah would have his blood placed on a wooden beam so that we could be freed from captivity to sin Exodus 12

That Messiah would come out of Egypt, as Moses came out of Egypt Hoseal 11:1

That Messiah would offer his life to save the Gentiles Jonah 1

That the Father would offer his Son as a sacrifice on Mt. Moriah (Jerusalem) Genesis 22

I could go on and on in this manner.  The claim that God did not make it clear in the Old Testament that Messiah would be offered as a sacrifice for our sin is an utterly false statement, coming from a person who, apparently, does not know the Old Testament all that well.

John Oakes