Oxygen is your friend. Find a technique that lets you breathe deeply. I have learned the hard way that staying in the saddle instead of standing up is actually more effective for me. Standing up is more physically demanding, ramps up my heart rate and sucks all the wind out of me. Also, keeping my hands on the top of the handlebars or on the hoods (instead of down in the drops) allows a more upright posture that lets my lungs inflate more fully. Although I have yet to figure out how it is done, I have heard that breathing with the diaphragm, like opera singers do, is the best way to fully inflate your lungs. Also, all advice about using your easiest gears and going slow while you are building up strength should be heeded. The great thing about hills is that there is always a top. Wind in your face....That's another story!! Keep on keeping on. You'll get there.