This is part 2 in my series of articles about Drupal widgets, and specifically creating a custom field. I recommend reading Part 1: Field type first, if you have not done so already.
After creating the field type it is now time to create the field widget.
a) Create the file
The field widget must be located as follows:
N.B. The field widget name should be in CamelCase.
In the newly created field type file add a brief comment to explain what it consists of: