My suggestion would be, if you can afford boarding one horse, try and find a barn where the people will help you learn about horses, handling etc. If you can't board, find one that will let you volunteer.
You have sort of put the cart before the horse - getting the experience first and then buying a horse would have been ideal. Not trying to criticize you, it just works a little easier if you can get hands on experience before owning one. It also helps you see where you abilities will go so when you do buy, you can buy one that fits your needs better. If you turned out to be a really talented rider, you may out grow both your horses.
If she intimidates you right now, can you stand outside the pasture gate, have her come to you and stop, then halter her and handle her that way. The more you handle her feeling safe, the more your confidence will grow. I would try and avoid situations that make you nervous or scared because she will pick up on that. Depending on her temperament, she may either get bossy with you which can be dangerous, or become nervous in your presence which will only intimidate you more.
But having someone knowledgeable around whether it's with your own horses, or at a barn will be a tremendous help. We all had to learn to be around horses in the beginning, so you're not alone there. I worked at a boarding barn doing weekend barn chores. At the start I had the manager or someone with me, then I did it all alone, but it helped me be comfortable and learn to start "reading" each horses behavior and how to handle their many different personalities/temperaments.