A Wiccan altar is a sacred place where you can perform candle magic. The altar is often considered a personal place where you can put the ritual items.
Most people use a table or sideboard as an improvised altar, and there is nothing wrong with this. There are benefits from having a designated personal sacred space for prayer, meditation, and ritual place that is used solely for your magic.
The purpose is the key to all magic, and this also applies to the altar itself. If you set aside a space for magic, with the intention of using it only for this purpose, it will develop a character and spirituality of its own. Whenever you find yourself in this space, even if it is a corner of a large room, you will immediately feel centered and secure.
Your altar can be as elaborate or as simple as you wish. A coffee table works well. Many people prefer working standing up, and a sideboard might be a better choice for them. Make sure that the altar is aesthetically pleasing to you.
The only essential requirement is a flat surface to work on, which means that you can use almost anything that appeals to you. It is an excellent idea to consecrate your altar by smudging it or bathing it in both sunlight and moonlight. To do this, place it outside on a sunny day for a few hours, and then allow the light from a full moon to bathe it for a few hours, too.
Some people cover their altar with a white silk cloth, which is often embroidered or decorated in some way. It is essential that this fabric is used only for its designated purpose. I have met people who have them in various colors. They use the correct planetary color for the particular ritual they are performing. It would be insulting to also use these planetary fabrics as tablecloths.
Many magicians have side tables beside their altars to hold any equipment required for a particular ritual. You should use a side table only if it can fit comfortably inside your circle.
Some people like to keep specific items on their altars. Goddess statue, Athamés, chalices, censers, pentacles, crystals, and wands are good examples. A Book of Shadows, tarot cards, and various other divination tools are also frequently found on altars. The items you keep on your altar are up to you. I use an altar cloth, and place on it only the items that are necessary for the ritual I am about to perform. Everything else is kept out of sight.