These are basically two steps.

Upload Instructor data in ViewBag

This step is simple. It can be done like this:

ViewBag.Instrutores = contexto.Instrutores.ToList()

Use @Html.DropDownListFor()

In View , you need to mount a SelectList within DropDownList . The usage may seem a little scary as below, but I'll explain the argument to make it clearer:

@Html.DropDownListFor(model => model.InstrutorId, ((IEnumerable<Instrutor>)ViewBag.Instrutores).Select(option => new SelectListItem
{
    Text = option.NomeInstrutor,
    Value = option.InstrutorId.ToString(),
    Selected = (Model != null) && (Model.InstrutorId == option.InstrutorId)
}), "Selecione um Instrutor...", new { @class = "form-control" })

The first argument is the field of Id :

model => model.InstrutorId

It reads as follows:

  

Having the model inside the variable model , use InstrutorId .

The second argument is the largest. It is not very complex, although it seems.

((IEnumerable<Instrutor>)ViewBag.Instrutores).Select(option => new SelectListItem
{
    Text = option.NomeInstrutor,
    Value = option.InstrutorId.ToString(),
    Selected = (Model != null) && (Model.InstrutorId == option.InstrutorId)
})

This part here:

((IEnumerable<Instrutor>)ViewBag.Instrutores)

Converts ViewBag.Instrutores (the one we selected in Controller ) to a list of instructors. IEnumerable is one of the List interfaces.

Then, we take this list and "select", for each element of it, an element of type SelectListItem :

Select(option => new SelectListItem
{
    Text = option.NomeInstrutor,
    Value = option.InstrutorId.ToString(),
    Selected = (Model != null) && (Model.InstrutorId == option.InstrutorId)
})

That is, we are actually creating, for each instructor, a SelectListItem , filled with the instructor attributes. Notice that I put each instructor in a variable option , and I need to fill Text (the field that will appear), Value (the value field, that is, the Instructor Id), and Selected indicates which field will appear selected, and what I do for the edit screen).

Finally, the third argument indicates the empty option text:

"Selecione um Instrutor..."

And the last argument are additional HTML attributes that you might want to use. This is to format the field as a input for Bootstrap :

new { @class = "form-control" }

How do I edit text in label ?

If you are not going to internationalize, decorate Model with

[DisplayName("Instrutor")]
public int InstrutorID { get; set; }

If it is, see this answer .