How to correctly implement file nesting in formit?

Question

MODX

Hello!
How to correctly implement an investment in formit so that it is correct. Have you never done this?
Looked on the Internet that did not understand.

<form action="" method="post">
  <div class="input-group mb-3">
        <div class="input-group-prepend">
           <span class="input-group-text" id="fa-user"><i class="fas fa-user"></i></span>
        </div>
            <input type="text" class="form-control" name="text" value="[[+fi.text]]" placeholder="Представьтесь*" aria-label="Представьтесь" aria-describedby="Представьтесь">
    </div>
    <div class="input-group mb-3">
        <div class="input-group-prepend">
            <span class="input-group-text" id="fa-envelope"><i class="fas fa-envelope"></i></span>
        </div>
        <input type="email" class="form-control" name="email" value="[[+fi.email]]" placeholder="Электронная почта*" aria-label="Электронная почта" aria-describedby="Электронная почта">
    </div>
    <div class="input-group mb-3">
        <div class="input-group-prepend">
            <span class="input-group-text" id="fa-phone"><i class="fas fa-phone"></i></span>
        </div>
        <input type="tel" class="form-control" name="tel" value="[[+fi.tel]]" placeholder="Телефон" aria-label="Телефон" aria-describedby="Телефон">
    </div>
    <div class="input-group mb-3">
        <div class="custom-file">
            <input type="file" name="files"  value="[[!+fi.files]]" class="custom-file-input" id="files">
            <label class="custom-file-label" for="files">Файл не выбран...</label>
        </div>
    </div>
    <div class="input-group mb-3">
        <div class="input-group-prepend">
            <span class="input-group-text"><i class="fas fa-marker"></i></span>
        </div>
        <textarea class="form-control" name="message" aria-label="Напишите, что вас интересует"></textarea>
    </div>
    <div class="input-group mb-3">
        <input class="btn btn-warning px-5 shadow-sm mx-auto" disabled type="submit" value="отправить">
    </div>
</form>

This is what comes out in the letter

Answer 1

Try addingenctype="multipart/form-data"

Answer 2

<form action="" method="post" enctype="multipart/form-data">