Our constitution is 66 years old. Regulations and the rules were framed That 62 years past still appear to be applicable in todays time. The inquiry appears Which Is That, our constitution makers were not so unwise That they had foreseen the changes which will take place? or is our constitution so good That it needs no changes.
Our constitution remains a living document. The Motives are: firstly, that our constitution accepts the needed changes Which is needed from the society. This Implies That our Judiciary has interpreted our constitution According Circumstances are changing. if you recall the keshavannada bharati case.
So, constitution is an instrument That modest demand changes from time to time. our constitution is not a static file also it could be changed. But at the same time it truly is a document that is sacred. our constitution is above normal law. It offers the framework to the authorities for democratic governing. That is why it is said That our Constitution is a living document.
Procedures to make amendment in Constitution

3 ways to make amendment in Constitution.
a. Simple Majority 
b. special Majority (Article 368)
c. The Majority special alongwith ratification to half of the state legislatures (Article368)

To know more about them ask separate question :)