You're new to this and so is your baby, so getting a nursing session off and running may take practice. Try this:
1. Hold her the right way. Nurses or a lactation consultant in the hospital can help you, or you can practice in a breastfeeding class before or after the birth. (While many books have breastfeeding illustrations, nothing beats having someone physically put you in the right position.) There are several possible holds, from the traditional cradle hold (belly to belly) or the football hold (baby beside you, her head at your breast). Whichever you use, baby shouldn't have to turn her head or strain to reach you.
2. Lift your breast with your free hand. Especially in the first weeks, your breast will be so heavy that you'll have to support it with your fingers. Holding it also helps you guide baby to it.
3. Hold your baby's back and neck with your other hand. Supporting those, rather than her head, will allow you to lift her easily.
4. Get her to open wide. You need baby to take half or more of the areola (the dark part around your nipple) into her mouth. Try tickling her cheek or lower lip with your nipple, then waiting for her to open as wide as a yawn.
5. Pull her to you quickly. Once baby's mouth is open, you need to get her on the breast fast, before she begins to close down. But don't bend down to her -- she'll get a better hold if you lift her to you. The hardest part: Getting used to moving her with confidence. You don't need to use force, of course, but you'll help her if you put her on gently but firmly. Her chin should press into your breast.
6. Check her mouth's position. Her lips should splay out, and you shouldn't be able to see much if any of your areola.
7. Relax and breathe. This is more for you than the baby. In the beginning, you may find yourself sitting stiffly, hunching your shoulders, and leaning over too far, which strains your lower back. Practice breathing slowly, relaxing your shoulders, and sitting back into the chair as much as you can.