The first thing a person would see when they entered God's sanctuary would be the brazen altar, also known as the altar of burnt offerings.
The dimensions of the altar were about 7 feet square and about 4 feet high. It was made of acacia wood covered with brass.
Every time a person committed a sin, whether in thought or in deed, whether by an action or a neglect of a duty, it was to this alter that they were to bring a live offering, such as a lamb. The animal had to be perfect, without any blemish. The person would place their hands upon the head of the animal and confess their sin to God. This action symbolically transferred the sin from the person to the animal. The person then had to kill the animal himself, catching the blood in a basin so that the Levites could later pour the blood out at the base of the altar.
The insides of the animal had to be cut out, cleaned with water and given to the Levites. They would then take the whole animal and burn it on the altar for the forgiveness of the sin committed. All of this was to show that in God's sight sin is a horrible thing, and that it was only by the shedding of blood that we could receive forgiveness of sins.
God does not enjoy the shedding of blood of an innocent animal. These animals all represented in one way or another the work of the Messiah, who was perfect in all His ways, yet was killed for our sins. And as you confess your sins to Him, asking for forgiveness and accepting His death for you personally, you can know that you are forgiven. And even more than this, you can know that your old lifestyle is dead, killed with Yeshua the Messiah. And since the Messiah has been raised to life again we can ask Him to give us a new life, and with His power not to do those sins again.
Picture originally found here