How to create @yield in @yield

how to make @yield inside @yield, because the second @yield does not bring up the content that I want to release??

I'm tired of finding ways to make @yield inside @yield.

because I want to use side navigation inside side navigation, so I need a way to make @yield inside @yield.

please help

//THIS IS MY FIRST @yield (mail.blade.php)
@extends('layouts.app')

@section('content')
<div class="mail-w3agile">
    <!-- page start-->
    <div class="row">
        <div class="col-sm-3 com-w3ls">
            <section class="panel">
                <div class="panel-body">
                    <a href="#" data-toggle="modal" data-target="#myModal1" class="btn btn-compose">
                        Compose Mail
                    </a>
                    <ul class="nav nav-pills nav-stacked mail-nav">
                        <li class="active"><a href=""> <i class="fa fa-inbox"></i> Inbox <span
                                    class="label label-danger pull-right inbox-notification">9</span></a></li>
                        <li><a href=""> <i class="fa fa-envelope-o"></i> Send Mail</a></li>
                        <li><a href="#"><i class="fa fa-star"></i>Favorit</a></li>
                        <li><a href="#"> <i class="fa fa-certificate"></i> Important</a></li>
                        <li><a href="#"> <i class="fa fa-file-text-o"></i> Drafts <span
                                    class="label label-info pull-right inbox-notification">123</span></a></a></li>
                        <li><a href="#"> <i class="fa fa-trash-o"></i> Trash</a></li>
                    </ul>
                </div>
            </section>
        </div>
        <section id="main-content">
            @yield('main-content')
        </section>
    </div>
    <!-- page end-->
</div>

@endsection

//AND THIS IS MY SECOND @yield (inbox.blade.php)

@extends('admin.mail')

@section('main-content')

    <h2>TESTING</h2>

@endsection

via Chebli Mohamed