Invoke SSIS from C#

Hi.

I am trying to invoke SSIS package from a c# code.  I also want to pass a parameter from my web code to ssis package. I tried the below:

private void InvokeSSIS()
        {
            try
            {
                string pkgLocation;
                Package pkg;
                Application app;
                DTSExecResult pkgResults;

                pkgLocation =
        @"LocalPath\Package.dtsx";
                app = new Application();
                pkg = app.LoadPackage(pkgLocation, null);  // error in this line
                pkgResults = pkg.Execute();
            }
            catch (Exception ex)
            {

            }
}

I am getting the error - No overload for method 'LoadPackage' takes 2 arguments 

Also, how should I pass a parameter to ssis package ?

Thanks