You don't need anything fancy, just a place to put your stuff while you do ritual and/or magick. A mantel top, a coffee table, a bureau top.
How you place objects on your Altar depends upon your Element associations. If you're using incense to represent Air, and Air for you is North, then you need to find north on your Altar, and put your incense there.
A traditional Altar has the tools representing the four elements in their respective directions, the four quarter candles, in their respective directions (more on color in a minute); three candles for the Lord, the Lady and the All That Is (or Spirit, if you prefer) ATI or Spirit in the center, you decide which half of the Altar is male and which female (traditionally left side is female) and place deity candles appropriately.
Anything else to go on, such as ingredients for a spell that need to be charged, seasonal decorations, and so, goes in places that
Now, my altar is small, it's a slice of maple tree and is only 13 inches in diameter. I can't fit all of that on my altar. So I place the quarter candles in their corners — I would love to have those wrought iron floor candlesticks, but for now I use shelves, or a chair seat to set the holder upon. I also tend to put the elemental representative tools on those makeshift shelves that sit beneath the altar, my slab of maple sits on a hand-carved mahogany base from India.
Other things that might go on there would be things sacred to your particular Gods. Keys are a sacred symbol of my Lady, I have an antique skeleton key hanging over my altar.
So much for arranging the altar, but where should the altar itself be? Tradition has it most commonly in the East, esp. as East is generally associated with the rising sun = new beginnings. North is another popular spot, being considered the womb/tomb = place of all endings and beginnings. Center is the third most popular spot, where it can be the focus for a the question of which direction is moot. Find out which direction and utilize it to the max.
My altar, being small, is mobile. While I was deeply involved in tracing my family tree (an on-going hobby with periods of intense focus), it seemed my altar.
While there, it collected things like — a sheaf of wheat, an iron spike from the railroad, a spindle. Suffice to say, it doesn't matter where you put your altar, so long as you know what it means. never do anything magickally or ritually that you can't answer.