Here's an small example how to send a transaction using NodeJS for the backend.
Don't forget to import the WIF, you can the wif by exporting it from Poltergeist or Ecto Wallet.
Here's how to import the wallet keys.
Here we'll create the script that will be sending the transaction.
/**
* Send a transaction
* @param transaction Transaction to send already signed
*/
async function SendATransaction(transaction: Transaction){
let transactionSignedBytes = transaction.toString(true); // Get the transaction in bytes convert it to string
let txHash = await RPC.sendRawTransaction(transactionSignedBytes); // Send the transaction to the network
await delay(5000); // Wait 5 seconds or more
let result = await GetATransaction(txHash); // Get the result of the transaction
return result;
}