The trick with hills, I've found, is gearing and pacing.
The most important thing is to ride at your own pace. If your buddy is used to climbing and you try to keep up with him, that's a recipe for frustration. Buy a heart rate monitor and use it to ensure that you're not continuously operating "in the red zone". When I started climbing, I really had a problem with trying to ride up the hill too fast, which meant I burned out long before the top. As soon as I started watching my HR, I had much more success. I was going slow (<5mph in some cases) but making it to the top.
Gearing is also important. With climbing you need to be able to find the right balance between mashing a difficult gear (which quickly saps your leg strength), and spinning an easy gear (which exhausts cardiovascular strength). If you're riding a typical road bike (53/39 chain rings, 11-25 or 11-26 cassette) you may find that switching to a "compact" crank (50/34 chain rings) or a wider cassette (e.g. 11-28) or both helps improve your ability to climb. I've been climbing with 50/34 rings and 11-28 cassette for the last year and I'm almost tempted to try moving back to a standard 53/39 crank. Almost!