Upload file by user

I would like to upload file from user form. When I search for the solution, I found that EpiServer.Forms support file upload but we are not using Forms for the pages and created programmatically.

For example, we are creating a page element using the following code

[Editable(true)]
[Display(
Name = "Name",
GroupName = SystemTabNames.Content,
Order = 10)]
public virtual string userName { get; set; }

Is there any way to upload file from user forms?

Also, Geta.Epi.MediaReferenceSelector can be used with following UI hints

[UIHint("ResponsiveMedia")]
[UIHint("ivpropertymedia",PresentationLayer.Edit)]

What is the variable type to use for MediaReferenceSelector?