<?php
require_once(dirname(__FILE__) . '/../lib/Coinbase.php');
// Create an application at https://coinbase.com/oauth/applications and set these  values accordingly
$_CLIENT_ID = "83a481f96bf28ea4bed1ee8bdc49ba4265609efa40d40477c2a57e913c479065";
$_CLIENT_SECRET = "a8dda20b94d09e84e8fefa5e7560133d9c5af9da93ec1d3e79ad0843d2920bbb";
// Note: your redirect URL should use HTTPS.
$_REDIRECT_URL = "http://" . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
$coinbaseOauth = new Coinbase_OAuth($_CLIENT_ID, $_CLIENT_SECRET, $_REDIRECT_URL);
if(isset($_GET['code'])) {
  // Request tokens
  $tokens = $coinbaseOauth->getTokens($_GET['code']);
  // The user is now authenticated! Access and refresh tokens are in $tokens
  // Store these tokens safely, and use them to make Coinbase API requests in the future.
  // For example:
  $coinbase = new Coinbase($coinbaseOauth, $tokens);
  try {
    echo 'Balance: ' . $coinbase->sendMoney($to, $amount, $notes=null, $userFee=null, $amountCurrency=null) . '<br>';
    echo $coinbase->createButton("Alpaca socks", "10.00", "CAD")->embedHtml;
  } catch (Coinbase_TokensExpiredException $e) {
    $newTokens = $coinbaseOauth->refreshTokens($tokens);
    // Store $newTokens and retry request
  }
} else {
  // Redirect to Coinbase authorization page
  // The provided parameters specify the access your application will have to the
  // user's account; for a full list, see https://coinbase.com/docs/api/overview
  // You can pass as many scopes as you would like
  echo "<a href=\"" . $coinbaseOauth->createAuthorizeUrl("balance", "buttons") . "\">Connect with Coinbase</a>";
}
Here is the send money code
public function sendMoney($to, $amount, $notes=null, $userFee=null, $amountCurrency=null)
{
    $params = array( "transaction[to]" => $to );
    if($amountCurrency !== null) {
        $params["transaction[amount_string]"] = $amount;
        $params["transaction[amount_currency_iso]"] = $amountCurrency;
    } else {
        $params["transaction[amount]"] = $amount;
    }
    if($notes !== null) {
        $params["transaction[notes]"] = $notes;
    }
    if($userFee !== null) {
        $params["transaction[user_fee]"] = $userFee;
    }
    return $this->post("transactions/send_money", $params);
}