Update README.md

Author: kimbtech

README.md

@@ -3,7 +3,59 @@
 > Easy and intuitive window positioning for electron browser windows.
 >
 
-Where to open an ...
+When opening an Electron BrowserWindow one have to define an position or use the default, which centers the
+window over all screens.  
+On some systems the default centering won't open the window on your current screen, e.g. the window could open on a monitor 
+which is switched off.
+
+This package detects on which screen the users mouse is and centers the window on that screen. Or opens it in the top
+left corner of that screen.
+
+## Installation
+```
+npm install electron-window-position --save
+```
 
 ## Usage
+```node
+const electron = require('electron');
+const WindowPosition = require( 'electron-window-position' );
+
+// Open window on electron.app.ready
+new WindowPosition( function ( pos ){
+  mainWindow = new electron.BrowserWindow({
+      x: pos.x, 
+      y: pos.y,
+      width: 300,
+      height: 300,
+      show: true,
+      resizable: false
+  });
+});
+```
+
+```node
+const electron = require('electron');
+const WindowPosition = require( 'electron-window-position' );
+
+// Get position for centered window
+var position = new WindowPosition();
+try{
+  var pos = position.getActiveScreenCenter(300,300);
+  
+  mainWindow = new electron.BrowserWindow({
+      x: pos.x, 
+      y: pos.y,
+      width: 300,
+      height: 300,
+      show: true,
+      resizable: false
+  });
+} catch (e) {
+	// electron.app not ready
+}
+
+```
+
+See also JSDoc at [GitHub Pages](https://kimbtech.github.io/electron-window-position/WindowPosition.html)