They don't "stand for" anything. The Lord and Lady are Deities, not symbols (though some Wiccans see them as symbols.) Wicca is a religion first, and a magickal system second. The Lord and Lady of Wicca are also known as the Goddess and the Horned God, or by secret names specific to each coven or tradition. Also, the High Priest and High Priestess in initiated coven traditions are given the title Lord and Lady, because they represent the God and Goddess during the ritual in a similar way that a Catholic priest represents Christ during the Mass. Wiccans believe that all Gods are One God, and all Goddesses are One Goddess -- so all the different Pagan deities in all the different cultures of the world are seen as aspects of the Lord and Lady. But there are many other Pagan paths under the umbrella of Neopaganism that hold a different view. Many Reconstructionist Pagans see all the different Gods and Goddesses as separate entities, not just different names of One God. Some Pagans see the Gods as aspects of their own minds, or Archetypes of the Collective Unconscious, and some Pagans see them as actual deities. Personally, I am a polytheist -- I believe in many Gods, not just two, and I believe that they are Gods, not just mental constructs.
But, if your interest is in the Magick and not the Religion, then study and practice Magick from multiple sources, and adapt it to your personal beliefs (and call it Magick, don't call it Wicca). Like Prairiecrow said, use the name of your own God to consecrate the candles. Magick depends on the relationship you already have with Deity. So, call on the aid of a deity with whom you have a relationship.