How to start mining pool? Can I start p2pool in shared hosting?  If yes, how to install p2pool ? 
I am newbe in this field. What are the pre-requirement for starting pool business ?
 Which is best script for pool ?  Github is down now ?
The short answer is yes. P2pool source code is available at https://github.com/forrestv/p2pool. If you stand up a P2Pool proxy (probably hundreds of them on the Internet actively running) such a server will maintain its own P2Pool sharechain state. As most mining pools, you will also need an active full node of the Bitcoin blockchain to validate the transactions being mined are indeed legitimate. Other miners can connect to your P2Pool proxy (that is part of the distributed P2P network) using either Stratum or GBT protocols that both bfgminer or cgminer support. Those same miners don't have to be sharechain-enabled. The P2pool sharechain is transparent to them. P2Pool supports numerous other alternative coins, and as a P2Pool proxy service you can reap additional merged mining benefits beyond the fixed mining fees established.