Originally Posted by Cheshyre

you're fine. climbing isn't a skill that comes overnight.
i think the best advice i ever got came from bicycling magazine (yeah, i know). ride up the hill at 80% of your max effort, even you're going only 10 mph. keep your cadence at 90+, and every now and then, click up a gear and climb standing for a bit. try to not get to the stage where your legs are screaming in agony.
also, i find this helps me a lot, on climbs, i move my hands to the bar-top position, sit up straight, and sit far back on my saddle. i pedal in a fashion that kind of makes my heels lead the downstroke on the cranks.
shift up earlier on hills.
when you get to the top, you won't feel that tired, and you'll be able to just fly down the other side at a respectable speed while still being able to do the little bit of recovery you need. if the top of the hill ends up just being a plateau, then you'll still be able to recover faster than somebody who's totally tapped out.
i'm a pretty crap climber and i get left behind on longer hills a good amount on group rides, but now, i always manage to recover quite quickly and catch up, usually to the surprise of the group. don't worry if you lag, you'll be able to catch up when they're tired after clearing the top of the hill.