someone has an apple ID and it has locked my phone? how do i get off it? and unlock it?

You can't get in unfortunately since it is in activation lock

You'd need to have them turn off find my iphone from icloud.com

If they won't do that for you, I'd look into a refund. There is no way to bypass this feature

You have to ask the seller to unlock it otherwise you have a brick and it will be useless to you.

Tell the seller to do this:

http://support.apple.com/kb/HT5661

Take it back where you got it. Without the credentials used to lock it, it's a brick. That's the whole point of activation lock. There is a very good chance the phone is stolen.