It's pretty easy to get going.
You could use npm bitcoin: https://www.npmjs.org/package/bitcoin
It just converts a method call to a bash command.
For example you want to generate a new address in your wallet you could connect to your bitcoind client and execute
if (err) return console.log(err);
console.log('New Address:', address);
});
or you could just do it by implementing the above mentioned library in your code.
To make a connection to your node call this:
var client = new bitcoin.Client({
host: 'localhost',
port: 8332,
user: 'username',
pass: 'password',
timeout: 5000
});
With the client variable you can now execute its implemented methods:
if(err) return err;
console.log('Address: '+ address);
});
Also, if you want to get started and do not want to download the whole blockchain, blockchain.info has a wallet API for you to play: https://blockchain.info/de/api/json_rpc_api