Design of a state observer for an inverted pendulum cart system.

Hello there, please am working on designing an optimal controller for an inverted pendulum on cart system. I have been able to come up with my systems LQR (K) control gain values and also I was able to compute my linear observer matrix for the system. I have gotten my observer matrix L but I dont know how to get the state estimation of my system states as that is my main challenge. I want the state estimation to be in form of a graph plot. Please assist me on how to go about this. Thanks in anticipation