Donate to optifine, or buy minecon tickets. (I have a optifine one)
you can download capes
you need to wear a differant skin the first skin pack with capes is the halloween limited edition but its not there anymore but the festive pack has skins with capes
That person will have either gone to minecon (2011/2012) or was given a cape by Notch or is a Mojang Employee
People with capes have either done something for Notch (the creator of Minecraft), or have bought a ticket to Minecon in either 2012 or 2011. Capes cannot be manually made into your skin, they are specially obtained. My advice if you want a cape is to attend Minecon 2013! All you have to do is buy the ticket and put in your username.
Dye is most commonly used to colour capes, but they are also used in several quests.
The Capes ended in 2008.
The Capes was created in 2002.
Lee Capes was born in 1961.
Lewis Capes was born in 1971.
The population of Preston Capes is 188.
Myriam Capes was born in 1984.
Bernard Capes died in 1918.