Stand in front of it, pull your pants down or give your penis enough freedom to have a clear look at the Urinal, aim at it and let the urine run. Make sure to joggle your penis around a bit at the end to get the last drops out.
Stand in front of the urinal and unzip your pants. While you pee aim for the drain at the bottom. When you are done zip your pants back up and flush the urinal. There is usually a handle on the top by the pipe that brings water into the urinal.