Subdivision basics


I am new to using Blender and have been watching several of the video tutorials. Having a little issue with the basics of editing a mesh.

Following the tuts, I have a new scene, added a plane, selected edit mode and added a subdivide. Then in the vid, he simply extrudes the edges. Now he has a box selection tool that he select the edges/verts with and extrudes, I cannnot find this, and am unable to follow.

Video found here:

Subdivision surfaces, right at the start basically.

Any help be appreciated.