Balanced equation: 2C6H8O6 + O2 = 2C6H6O6 + 2H2O

So I've balanced the equation, and the question is: How many mole of oxygen gas is required to react with 1000.0mg of vitamin C.

I got as far as this;
mols vitamin C= grams/molar mass
= 1g/ 176.12706

I'm really confused and not sure if I'm going in the right direction and don't know where to go from here