How to write a Widget for Orchard CMS? Coding, Packaging and installing

1. Coding:
http://orchardproject.net/docs/Writing-a-content-part.ashx
http://orchardproject.net/docs/Writing-a-widget.ashx
2. Packaging:
http://www.orchardproject.net/docs/Packaging-and-sharing-a-module.ashx
3. Installing:
http://www.orchardproject.net/docs/Installing-and-upgrading-modules.ashx