First off, I don't know if this belongs in magic items, if it doesn't than I am sorry. Second of all, I have no idea what it does. Ok I have 'some' idea, but not enough. Third of all, how do I create one? Once I have the knowledge of what it does, I plan to make one but I don't know how. Thanks for any help you can give me.
I quick google search would have helped you here, but an altar is basically a magical or religious working or worshipping space. Many people have altars dedicated to specific gods they are worshipping.
That being said, how you would go about making your altar varies on the tradition, practice, and religion you follow.
An altar is a place where you honour the gods and goddesses (or just one deity it depends on tradition).Is also a sacred place where you interact with a specific deity.
You can use a table (clean) and put on it candles,statues,magical items (athame,cauldron,incense).
This article expalin it betterhttp://www.spellsofmagic.com/read_post.html?post=506217