Add usage examples

README.md

@@ -3,6 +3,49 @@
 
 Vereign’s JavaScript library is an asynchronous library that allows for digitally signing your email and in-browser documents, data encryption, and key-based authentication.
 
+## Usage
+Add library as inline script.
+```html
+<script type="text/javascript" src="./viamapi-client.js"/>
+```
+
+Initialize library
+```js
+// Target container used to append iframe
+const containerId = "root";
+
+// Required methods used to be called within iframe.
+const methods = {
+  onEvent(event) { console.log(event) }
+};
+
+// Iframe URL to connect 
+const iframeUrl = "https://test.org/iframe";
+
+// API url used to access endpoints
+const apiUrl = "https://test.org/api";
+
+this.library = setupViamAPI(containerId, methods, iframeUrl, apiUrl);
+
+this.library.then(lib => {
+  this.listenerUUID = this.addListener({
+    callback: function(event) {
+      handleEvent(event);
+    },
+    filters: [
+      "IdentityNotLoaded",
+      "ActionConfirmedAndExecuted",
+      "Authenticated"
+    ]
+  });
+
+  lib.listIdentities().then(response => {
+    this.setState({ identities: response.data });
+  });
+});
+```
+
+
 ## Development
 
 ### Running