Everyone needs to find their own deity in their own way.
Most forms of Wicca call for a Lord and Lady, a God and Goddess. Most forms of
Wicca allow for a Witch to substitute a God or Goddess other than the main ones for a specific ritual.
So, how do you know which God or Goddess (or one of each) is yours?
If you are part of a coven or other group, you can seek the assistance of your
high priest or high priestess, who may have a ritual to assist your search. If you are a solitary or your group is all beginners,
then you will need to conduct your own search.
For some people, the God and/or Goddess comes to you. This can be a visit in a
dream, a vision that occurs during ritual, or some other sign or message from your God and/or Goddess.
For many people, you have to search for your God and/or Goddess. The easiest method
is to start researching Gods and Goddesses from around the world. After enough research, many people encounter a God or Goddess
that appeals to them. Once you find a God or Goddess that seems right, you can use meditation, divination, or other ritual
to confirm the choice.
In the meantime, it is perfectly acceptable to invoke a generic "Lord" and "Lady"
that represents all of the Gods and Goddesses. You can also experiment with different Gods and Goddesses that you have read
about, especially if you match up those Gods and Goddesses to rituals that are related to them.
It is also possible that you might find more than one deity that fits you personally.
It is fairly common, for example, for someone to use two different Goddesses in their ritual, balancing which one fits their
needs at any given moment, or even invoking both at the same time. The pairs can be deities that are related mythologically
(such as sisters or mother/daughter) or could even be two apparently unrelated deities from completely different traditions
(sometimes they turn out to be more related than you first thought, for example, many people are drawn to Artemis [Greek]
and Diana [Roman] or Artemis and Bast [Egyptian] and then later find out that the ancients thought that Artemis, Diana, and
Bast were all the same Goddess).
Spirit guides are a shamanic tradition, but many Witches use spirit guides. Without
going into too much detail, a person finds his or her spirit guide by going on a vision quest. These are usually very involved
rituals and you probably need the help of an experienced shaman to try this. Usually the spirit guide is in the form of a
animal. This animal might also become your totem. In some forms of Witchcraft, once you know your God and/or Goddess, you
might have an animal spirit guide provided by that God or Goddess (and the animal spirit would be an animal associated with
that deity, for example, Bast is Goddess of cats).