If you feel frustrated, stop. You will need to be relaxed. Start by collecting a container in which to collect the milk. Make sure it is clean. You can use hot soapy water to clean container.
Any container is fine.
With practice, you will be able to express right into a nurser bottle. Next wash your hands. Place a warm wash cloth on your breasts for a short time to help stimulate the letdown reflex. This reflex allows breastmilk to flow from the milk glands. Massage your breasts, as well.