how to solve error from sending email from contact form

I am trying to send mail from my contact form. But I am getting error.

contact.blade.php is:

<form method="post" action="">
                    
                              <table align="center" width="400">

                                  <tr>
                                      <td><strong>Full Name</strong></td>
                                      <td><input type="text" name="name" required="required" /></td>
                                    </tr>
                                  <tr>
                                      <td><strong>Contact No.</strong></td>
                                      <td><input type="text" name="mobno" required="required" /></td>
                                    </tr>
                                  <tr>
                                      <td><strong>Email ID</strong></td>
                                      <td><input type="text" name="email" required="required" /></td>
                                    </tr>
                                  <tr>
                                      <td><strong>Message</strong></td>
                                      <td><textarea name="msg" cols="30" rows="3" required="required"></textarea></td>
                                    </tr>
                                  <tr>
                                      <td>&nbsp;</td>
                                      <td><input type="submit" name="submit" /></td>
                                    </tr>
                                </table>
                                </form>

web.php is:

Route::POST('send', 'ContactController@send');

ContactController.php is:

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use App\officeholder;
use App\Mail\SendMail;
use Mail;

class ContactController extends Controller
{

public function send()
{
    Mail::send(new sendMail());
}
}

I have created SendMail.php using php artisan make:mail SendMail by my cmd and then App\Mail\SendMail.php is created.

SendMail.php is:

<?php

namespace App\Mail;

use Illuminate\Bus\Queueable;
use Illuminate\Mail\Mailable;
use Illuminate\Queue\SerializesModels;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Http\request;

class SendMail extends Mailable
{
use Queueable, SerializesModels;


public function __construct()
{
    //
}


public function build(Request $request)
{
    return $this->view('contact',['msg'=>$request->msg])->to('mymail@gmail.com');
}
}

But I got error after click button on form.

1/1) FatalErrorException Class 'App\Http\Controllers\sendMail' not found

in ContactController.php line 18

via Chebli Mohamed