Open the Hypershade (Window > Rendering Editors > Hyprshade).

This is where textures and materials are created. If you're not sure how it works, try taking a look at my Hypershade Overview at my...

For the step in question, he grabbed all of the points except for the ones on the outer edges and moved them in the X or Z direction until they lined up with the drawing's furthest point.

In the...

Ah, yes, I believe the right click Materials menu is a Maya 4+ feature, sorry.

In that case, you'll have to create a material in the Hypershade (Windows > Hypershade, I believe. Windows >...

The step in question is going over how to create your image planes in Maya to use as reference while modeling (something I'd definitely recommend doing as much as possible). To ensure your planes are...