I totally agree with what the other ladies here have said, but I also want to add that it just takes time. You have to build your fitness. Even if you are fit, when you start riding you have to build your BIKE fitness. Just keep riding. It will get easier. Hills are always a bugger. It kinda cracks me up when people say, "just pick a gear where you can spin up." Well, that gear doesn't exist for me. Hills are simply tough and it takes time to build the bike fitness to just spin up them.

I got my MTB about 2 years ago and my road bike one year ago. DH and I do lots of hills and I have ridden a century. We just did one of our usual routes the other day, and for the first time I noticed I could go faster on one of the the hills.

You just need to be patient with yourself, not beat yourself up, and keep working on it.