virtualmonger- congrats on wanting to bike commute.

Some cautions are called for. Fifteen miles is a very long commute and especially for someone just learning to ride: if you don't adequately prepare it will be exhausting and dangerous.

Get a bike and ride it around your neighbourhood for a few weeks, including maybe a couple of weekend test rides to school

Read books on cycling in traffic like this one: ECWPress
or this one: http://www.amazon.com/Art-Cycling-Bi.../dp/0762743166

Scout out the safest routes.

Practise riding in a straight line, and doing shoulder checks without veering

etc.