Readme update

README.md

@@ -2,14 +2,42 @@
 
 > It is a PHP port of [ramoona's banks-db](https://github.com/ramoona/banks-db).
 
-Returns bank's name and brand color by bankcard prefix (BIN, Issuer Identification Numbers, IIN).
-
-> It's a community driven database, so it can potentially contains mistakes.
-
-For UI examples see the [original library](https://github.com/ramoona/banks-db).
+Returns bank's name and brand color by bank card number's first digits (BIN, Issuer Identification Numbers, IIN).
 
 ### Installation
 
 ```
 composer require chekalskiy/php-bank-db
-```
+```
+
+### Basic usage
+
+```php
+$card_prefix = $_GET['card_prefix']; // we only need first 6 digits
+
+try {
+    $bank_db = new BankDb();
+    $bank_info = $bank_db->getBankInfo($card_prefix);
+
+    $result = [
+        'is_unknown' => $bank_info->isUnknown(), // is bank unknown
+        'name' => $bank_info->getName(true),
+        'color' => $bank_info->getColor(),
+        'type' => $bank_info->getCardType(),
+    ];
+
+    return $result;
+} catch (BankDbException $e) {
+    // todo handle exception
+}
+```
+
+### Contributions
+
+Feel free to open [an issue](https://github.com/chekalskiy/php-bank-db/issues) on every question you have.
+
+---
+
+> It's a community driven database, so it can potentially contains mistakes.
+
+For UI examples see the [original library](https://github.com/ramoona/banks-db).