If you are looking to design shoes on your computer using software, here are three options:

1.  Digital Fashion Pro software with their Shoe Factory add-on.

You can make limitless designs on over 125 templates using this software.  They even have digital fabrics so you can give your shoes a more realistic touch.  Numerous art and design schools use this program.  Check out this video:

2. Adobe Photoshop

If interested in this method, you will need Photoshop, the skills to use it, and shoe templates.  Shoe templates can be found around the net, but here is a link to some examples:  pigmag’s official sneaker templates.  The video below shows this method (I apologize for his choice of music).

3.  SketchBook Pro 2010

Sketchbook is great software for those that want to get into designing and digital art, but also might require the most skills and patience.  In addition, it is highly recommended you use a drawing tablet with  Sketchbook.  Here are two videos of the tutor from sketching a design for a basketball shoe (again I apologize for the music).