First off to get good you will just have to resort to doing more hills. That said to be a better climber it takes patience and a solid planned routine to build the right base through good technique, endurance and eventually strength.

Start slow and work on spinning with a high cadence to build aerobic endurance

After several weeks to months you can start working on doing the same hill repeats in one lower cog in the rear cassette

Next up shoot for timing how long it takes you to climb those hill repeats and start by knocking off 15 to 30 seconds off a single climb. Other options are to do it with full water bottles, camelback etc to increase the workload.

Focused efforts over 5 to 6 months will really show some results and you will find yourself passing others on the middle to upper tiers of climbs on group rides. Oh, don't forget to look over and smile as you go by.

Climbing is demoralizing to most people so you need to also look at it with a positive attitude that you enjoy climbing and will be (are at some future date) a good climber.