It only takes clipping into the quick one time and they never get over it. But, I imagine it is pretty painful.
Get someone to help you. Gently but firmly hold the pup in your arms, one arm under the belly and the other one under the neck/head with you hands up toward your shoulders. Hold them up, off of the table, so that they can't push with their legs. A groomer/vet tech showed my husband and me how to do it this way. It makes the job a lot easier and doesn't stress all of us out. My DH holds them and I clip their nails.
Hold the paw with one hand and clip the nail front to back, not side to side. If her nails are real long, just clip a little at a time over a few weeks time, because the quick will recede as you do this. If you clip too much at first, you will clip into the quick and she will always be afraid. It is good to have some styptic powder on hand in case you do clip into the quick to stop the bleeding.
There are YouTube video on clipping nails too.