I was raised without a definite religion, my mom decided to be a christian. Jewish blood runs high in me, as my grand mother and mom are completly jewish, and i wish to be jewish. what is neccesary to be a jew, or am i already a jew? please help, thank you.

If your mother is Jewish- you are Jewish. You should contact an Orthodox rabbi in your area with the documentation of your mother's Jewishness and ask him to assist you in learning more about Judaism and Torah.