Is this launched? If yes where are the nodes?
Running
https://github.com/OpenNetworking/gcoin-community/wiki#runningPlace a configure file in ~/.gcoin/gcoin.conf with the following contents (you don't need to modify anything)
addnode=140.112.29.201:12321
addnode=54.254.159.145
rpcuser=username
rpcpassword=password
Now, run the demand!
./src/gcoind -daemon
It would automatically synchronize the Gcoin test net blockchain. You should be able to use the RPC after runs the daemon. Here's a quick way to test:
./src/gcoin-cli getinfo