Prove that

$\displaystyle \frac{1}{\sqrt{n}}\left (\sum_{i=1}^{n} \frac{\partial l(X_{i};\theta )}{\partial \theta } \right )\overset{D}{\rightarrow}N(0,I(\theta ))$

Where l(X_i; θ) is the log likelihood function and I(θ) is the Fisher Information.

How would I go about proving this?