Modal ajax in asp net mvc, how to do?

Personal I'm using the asp net mvc template to create a website, it's in the one page style. In it I created a modal, so it is loading blank. See below how I developed:

Here in my index.cshtml file:

<div class="image-item">
                <div class="image-box inner-title image-hover">
                    <div class="image">

                            <a href="@Url.Action("_VenderSempre", "Home")" data-toggle="ajax-modal"><img src="~/Content/img/vender-sempre.jpg" alt=""></a>
                    </div>
                    <div class="title">
                        <a href="@Url.Action("_VenderSempre", "Home")" data-toggle="ajax-modal">
                            <h2 class="mb-0">Vender Sempre</h2>
                            <p class="lead text-muted mb-0">Técnicas de PNL e Persuasão para você vender muito mais</p>
                        </a>
                    </div>
                </div>
            </div>

And here is my partial view _VenderSempre.cshtml that should display the message "testing modal":

<h2>
    testando modal
</h2>

Is it missing to reference something? Can anyone help me ??