Hi. You don't need a bridge, you can use the app.* methods in your webview by adding this script tag at the top of your html file:
<script src="ds:/Sys/app.js"></script>
Make sure your html file is located at the root of your project directory.
If you really want to use a bridge, you can use the web.Execute(code) or web.Func("funcName", arg1, arg2) where "funcName" is a function defined globally in your webview.