The 10 commandments was not the only part of the Law. The Law included directions for the tabernacle, instructions for the altar, Levitical Priests, animal sacrifices, the tithe, and more. Exodus 25-31 and pretty much all of Leviticus explains and covers it all. The important point to remember is that this is the Law & covenant that God gave to the children of Israel. It was only meant for the Jews, so only if you are a descendent of one of the 12 tribes of Israel should anyone refer that they are under the law. That's a very big point to understand at the simples
Belief in Jesus, his life, sacrifice, & resurrection is the New Covenant. Jesus was born from the line of Judah, the bloodline of King Solomon & King David. He was a Jew. Through His life & ministry on earth, he was sinless. He resisted the devil 3 times starving in the wilderness. He did not sin, but was persecuted and crucified nevertheless. He was the only one who fulfilled the Law. Explaining Matthew 5:24, he didn't come to destroy the Law, but He fulfilled it. He was the only one who lived a perfect life, therefore fulfilling the Law.
If you read the scriptures in Part 3, you would see there is constant reinforcement of the fact that we are not under the law. That point should be drilled in. God gave Israel the Law, but later gave everyone grace if we accepted it. The Jews at the time didn't have a choice, it was the law of their people