I need to know a lot of the symbolism behind the short story "The Masque of the Red Death."

You have certainly done well to identify the importance of symbolism in this great short story. I will point out some of the major forms of symbolism and hopefully you will be able to use this to work out the meaning of the story. Remember though, that in Prospero and his revellers we are presented with people who want to try to escape the "Red Death" and lock themselves away in a bubble-world of pleasure. It is clear, though, that this escape attempt does not work.

Clearly the party contains lots of symbolism, mostly to do with the setting. Note how the seven rooms go from east to west, which symbolises the movement of the sun and the moon. This represents the life cycle, ending in death in the black room. The colours of the rooms are likewise symbolic. Note too the clock that is in the seventh room. The clock symbolizes time passing, which in this context means the approaching death. Note how every time the clock strikes it produces silence amongst the revellers - as if they recognise this fact, then hasten to forget it. It is key therefore that the intruder walks through all of the rooms into the final room, and it is only in this final room that Prospero confronts him - and dies. Thus begins the outbreak of the Red Death and Prospero and his revellers learn the essential lesson that nobody - no matter how strong, rich or powerful - can escape death. We are all subject to Death's dominion at the end of our lives.