Update README.md

README.md

@@ -6,8 +6,29 @@ PHP SDK for Airwallex API
 
 ## Installation
 
-The package [`vinkas/airwallex`](https://packagist.org/packages/vinkas/airwallex) can be installed using composer via packagist.
+The package [`vinkas/airwallex`](https://packagist.org/packages/vinkas/airwallex) can be installed using composer via Packagist.
 
 ```
 composer require vinkas/airwallex
 ```
+
+## Configuration
+
+Set the Airwallex Client ID and API Key values in Environment variables using the keys `AIRWALLEX_CLIENT_ID` and `AIRWALLEX_API_KEY`.
+
+## Usage
+
+Create a new `Client` instance and get the balances related endpoints like below
+
+```php
+use Vinkas\Airwallex\Client;
+
+$client = new Client();
+
+$balances = $client->getBalances()->getCurrent()->array();
+
+$balanceHistory = $client->getBalances()->getHistory()->object(); // Result will include records for the last 7 days by default
+$balanceHistory = $client->getBalances()->getHistory($from, $to)->object(); // $from & $to - any dates in ISO8601 format. max time range - 7 days
+```
+
+For more API-related details refer to https://www.airwallex.com/docs/api