Creatine does not add muscle directly like testosterone of HGH do but it certainly helps you to gain more muscle by allowing you use more energy in your workout. As we all know intensity is everything when it comes to building muscle at a regular rate. What creatine does is that it enables your muscles to produce more ATP and therefore have more energy to perform.
So the short answer is that creatine does not directly cause your muscle to grow but it certainly has an indirect effect on the way that you are able to call energy to your muscles which as a result will enable more muscle growth. There are many different sources of creatine that you can choose from and they range from supplements to powders.
Creatine helps to replenish ATP also known as short term energy, this energy is necessary to help give you the thrust to push your lift up. The formula is quite simple the heavier the weight and more repetitions you preform the more muscle mass you can expect to build. If this is your first time using a supplement like creatine you are more likely to see bigger gains with in the first few months.
The cell expanding properties that creatine contains helps volumize or make cells larger. When you take creatine and it goes into the muscle tissue it also brings additional water and the fluid works to increase your muscles giving them a larger look. Some might argue that this is simply water weight that will flush out which to some extent is true however with time it becomes pure muscle mass.
Science has conclusively proven that you will gain more muscle when your muscles are getting stronger. Initially your first gains while on a creatine supplement were belived to only be added water weight however through studies it has proven that this water weight eventually turns into lean muscle mass. With our bodies composed of over 85% water it makes sense.
In conclusion the gains that you get from supplementing with creatine phosphate are there because of the extra ATP or energy that you have at your disposal. It does not make your muscles grow faster and muscles take time to adapt to the strength changes that you are going through as you work-out with heavier weights.