if you are too shy to tell her just do the following:
1- hold her hand at any and everytime
2- always look to her in her eyes and smile,that means alot
3- tell her she is so precious
4- tell her you want to spend your life with her
5- tell her that she is a gift you can't thank god enough for it
6- don't be angry all the time
7- don't do anything except talking to her-when you are with her-
8- show interest in what she's saying even if it is silly
9- never ever lie to her
10-presents aren't always the solution, so just be yourself,honest and true