I'm not used to the forgotten realms camaign setting, Me having played more Dragonlance. I really like the cleric class and I already have a cleric made. However due to his alignment and domains, he only matched up with the great mother. I havn't any idea what she is or what one of her followers are to do to worship her, or even if a human should even be following her.

I also want to make a cleric for the god/goddess of luck, if you could tell me that god/goddess's name, and what alignment and domains are recquired, that would be great. I think a cleric of a god like that would be a very interesting character, so I'd appreciate your feedback.

You probably do not want to be a follower of the Great Mother. As for your second question, Tymora (or, alternatively, Beshaba for bad luck), but I'm too lazy to look up the specifics on her. You can find the details in teh Faiths of Faerûn section.