How do I add a custom dashboard lens to the dashboard?

First, you must register your lens:

\Aero\Admin\Facades\Admin::registerLens(\Aero\Admin\Lenses\OrdersLens::class);

Then you can add it to the Dashboard:

\Aero\Admin\Http\Responses\AdminDashboardPage::extend(function (\Aero\Admin\Http\Responses\AdminDashboardPage $page, \Closure $next) {
    // Add it as the first lens
    $page->addLens(
        \Aero\Admin\Lenses\OrdersLens::key(),
        \Aero\Admin\Lenses\OrdersLens::class
    );

    // Add it after a specific lens
    $page->addLensAfter(
        \Aero\Admin\Lenses\OrdersLens::key(),
        \Aero\Admin\Lenses\OrdersLens::class,
        \Aero\Admin\Lenses\RevenueLens::key()
    );

    // Add it before a specific lens
    $page->addLensBefore(
        \Aero\Admin\Lenses\OrdersLens::key(),
        \Aero\Admin\Lenses\OrdersLens::class,
        \Aero\Admin\Lenses\AverageOrderValueLens::key()
    );
});