How do I tell my girlfriend that I have a two year old daughter?

I think its great you're openly gay and dating with a daughter. I think you should tell her. Explain to her about the (no details needed, just that it was not your fault) and that you love your daughter very much. Also, explain to her that you do not expect her to help you raise your daughter, but you're still interested in dating her and you respect her enough to tell her because you do not want to keep secrets. Getting things like that out in the open is good, because if they find out later when you're in a deep relationship, it could ruin everything. If she feels that you two will not work because of this, don't worry. You will find someone to love you AND your daughter, but never hide her... she IS your daughter. Good luck with everything. Let me know how it goes.