No deposit contract specified.

[yahtoo]

when I start beacon from
./beacon-chain --datadir /home/xx/.beacon/ --rpc-port 4000 --demo-config --p2p-port 9000
[2019-03-07 10:37:40] INFO node: Using custom parameter configuration
[2019-03-07 10:37:40] INFO node: checking db
[2019-03-07 10:37:40] FATAL node: No deposit contract specified. Add --deposit-contract with a valud deposit contract address to start.
how can I get deposit contract ?

[0xKiwi]

Hello @yahtoo ! Thanks for using Prysm 😄

So, in order to start a beacon-chain node you need to follow the steps listed here:
#1565

They involve you deploying a deposit contract (the 1st command), starting the beacon chain node, and then setting up the 8 validators (followed by performing the 8 deposits) needed to begin chain start. We're currently working on this so apologies for the out of date docs.