In the book of Corinthians we see the Apostle Paul walk us through exactly what happen on the very night Jesus Christ was given up by Judas to be crucified.
In the book of John we see Jesus Christ Himself breakdown exactly what Communion represents and the importance of it.
"53Then Jesus said unto them, Verily, verily, I say unto you, Except ye eat the flesh of the Son of man, and drink his blood, ye have no life in you. 54Whoso eateth my flesh, and drinketh my blood, hath eternal life; and I will raise him up at the last day. 55For my flesh is meat indeed, and my blood is drink indeed. 56He that eateth my flesh, and drinketh my blood, dwelleth in me, and I in him. 57As the living Father hath sent me, and I live by the Father: so he that eateth me, even he shall live by me. 58This is that bread which came down from heaven: not as your fathers did eat manna, and are dead: he that eateth of this bread shall live for ever."