What is the process to set funnels for a site in Google Analytic?
What is the benefit of using it?
You should understand the benefit of using before asking how to implement it.
Please consider doing a basic search engine search, or visiting the source before posting questions here - we can help when you get stuck, but this forum isn’t for telling you how to pick your nose.
For setup the funnel , you need to know your objective for measurement first and then you set up the funnel via Goals , that you can set up url for each step of process, for example : Shopping Cart, User Details, Payment Details. When you implement Google Analytics, you will get the ideas why people leaving your site and what steps that people away from your site , also you can analyze source of traffic and behavior.