How do I apply the dental wax? (photo)

After about a week with my first tray of Invisalign I got terrible canker sores. My orthodontist had suggested that should this happen, I am to use Colgate Peroxyl (which I have been doing, and is providing temporary relief) and use the dental wax that she provided me. The dental wax is in hard tube shaped forms (see photograph) and I haven't any idea on how/where to use it! How am I supposed to use the dental wax, and where shall I apply it? Any help is much appreciated, Thank you!