Recent decisions in Glass Mapper headquarter caused removing free useful tutorials from their website. The best way to understand how it works today is to dig into their github repository. Glass Mapper 5 introduces few changes which completely change the way of mapping your model in razor view.

Previously we could use that line below to map our model with Glass Mapper:

@inherits Glass.Mapper.Sc.Web.Mvc.GlassView<Sitecorebond.Models.IExample>
Editable(m=>m.Title)

Using above code with Glass Mapper 5 will highlight and notify this method is obsolete and will be removed with next version ( GlassView is now obsolete. Use @html.Glass() helper methods ).

Quoting what they said on their website:

GlassView and GlassController are now marked as obsolete. These class will eventually go, they no longer offer any value and other better techniques are available.

You can read about all changes here: Glass Mapper V5 changes

As you can see they haven't provided any help or explanation to what do they mean by better techniques and figuring it out by yourself is a bit of a journey. But the change is really looking nice, check an example below:

@use Glass.Mapper.Sc.Web.Mvc
@model Sitecorebond.Models.IExample
@Html.Glass().Editable(m=>m.Title)

Looks nice and simple. But you have to be a wizard to find any information on how to use it or you can always pay few hundred $ on their online course hoping they cover V5 (today they don't). You should also make yourself familiar what IMvcContext class is hiding because this is what you will more likely use when working with glass in your backend.

Little example of casting items below:

    var homepage = _mvcContext.SitecoreService.GetItem<IHomepage>(new GetItemByItemOptions() { Item = Sitecore.Context.Item });
    var anyItem = _mvcContext.SitecoreService.GetItem<INotHomepage>(new GetItemByIdOptions() { Id = new System.Guid("00000000-0000-0000-0000-000000000000") });