It`s really simple and effective. All you have to do is squeeze the fleshy spot between your thumb and index finger. In Chinese medicine this place is also known as Hoku spot. Apply pressure for around 30 seconds and you`ll start to feel more relaxed and tension free. With any luck your headache should start to wear off soon.
NOTE: It`s really important to know what kind of headache you have in order to treat it correctly. If you are experiencing more serious problems go and see your doctor!