So you are a shy guy and you really like a woman and want to kiss her, but you just can't get up your nerve. Here's a little secret that should put you at ease. Think about it this way, how long have the two of you been spending time together? She wouldn't be spending time with you if she didn't like you. If she is with you she knows you are shy and is probably one of the things that attracts her to you.
Most of us women have already tried the bold, forward, egotistical man and realized they aren't what we want in our lives. They tend to get loud and obnoxious and end up embarrassing us more often than not. They tend to be pushy with no concept of "timing is everything." The man who is very sure of himself generally has no idea how to be soft and vulnerable.
So if a woman is with you the shy guy, it's because she knows what she doesn't want in a man. Now it's up to you, even though you are shy, to show her that not all men are the same. Show her who YOU really are. It's fine that you are shy, there is nothing wrong with that at all. Show her what she does want in a man. We women want someone who will listen to us and communicate with us. We like a man who is not embarrassed to hold our hand in public. We love it when a man's ego doesn't get in the way of his emotions.
You will need to get your courage up a bit. Start studying her, read her actions. Do you catch her looking at you when she doesn't think you are looking? When she looks you in the eye what do you see? Does she keep eye contact and hang on your every word? Does she sit or stand close to you when you are together? If she does these things she is opening herself up to you. She may be a bit shy too, but she is making herself available to you, also making herself vulnerable to you. This is a big step that is not easy for a woman.
She is waiting for you to make your move. When you are with her and the time feels rights, gently take her hands in yours so that you are facing one another. Look her in her eyes, and be completely honest with her. She will respect this, not ridicule you for it. Tell her how you feel about her. If you are still afraid that she won't return your kiss, tell her. Ask her if you can kiss her. I can almost guarantee you that you will get your kiss immediately.