I want to fork stellar and make a new blockchain,
1) how should I proceed? step by step.
2) how to keep that blockchain running.
3) what should I know before doing this.
4) Please refer to any reference material that I can use.
1) Setup three stellar-core nodes and configure them in a way that
Kickstart your network by restarting one node with the force-scp option.
2) Get as many other people as possible involved to run validator nodes on your network. The more validator nodes, the more stable your ledger. Ensure that at least two full nodes are up and running at any time.
3) Ask yourself for what reason you need your own chain and why this is not achievable on the stellar public network - I barely know a single good reason for running an own chain but a lot of reasons not to.