@ Alaa
At the moment I do not have a step by step on how to add custom fields, however, I can refer you to a couple plugins that I’ve released that creates custom fields which you can reference to build you own.
The first is the custom field demo plugin. It is very basic. It adds four metaboxes showcasing all of the fields that can be created using the Custom Field API.
https://github.com/Connections-Business-Directory/Connections-Custom-Metaboxes-And-Fields
The second is a fully functional, well documented plugin that adds a Income Levels field. This one will likely be a good base for you to base your on.
https://github.com/Connections-Business-Directory/Income-Levels
The last is a bit more complex as it creates and utilities a custom field type, a field type not supported by the API. Basically this plugin demonstrates that any type of field can be added.
https://github.com/Connections-Business-Directory/Hours
Hope this helps you, and if you want, send me yours, I’ll put it up Github for others.
