If you are learning to play guitar, one of the first things you need to know is how to properly hold a guitar pick
. Most people playing guitar use a pick in order to strum the strings. If you are a beginning player it is usually best to use a medium gauged pick. These are labeled with a "M" or will have a number between the gauges .62mm - .83mm printed on them. Make sure to pick up at least around 10 different picks, so you can find out which one is easiest for you to use. Experiment with different shapes, materials, gauges, and textures.
Holding a guitar pick can be very subjective to each individual. Many people have different techniques. However here is a description of the most common technique. Hold the guitar pick in your picking hand with your index finger and your thumb. If you are right handed, use your right hand. If you are left handed use your left hand. Make sure your thumbnail is facing directly towards you. Have your thumb cover about 1/2 of the top of the guitar pick at the widest point. Then rest the other side of your pick on the side of your index finger. Do not clench your fist. Keep a nice half circle appearance with your thumb and index finger. Some people also hold the pick between their middle finger and thumb. It is a matter of preference, so just try whatever feels best to you and gives you the most control over the pick. Also make sure not to hold the pick too tightly.
Then just lots and lots of practice, eventually you will get the the feel, and you will make your own personal adjustments when holding the guitar pick.