How can I add Contact Number to Alumni Registration Form

Could you help me to customize alumni public registration form. I want to add Contact Number field to the form.

Hello! Welcome to the wonderful world of Gibbon module development. We have some documentation available that can help you to work on a module, found at this link. Once you’ve worked out the logistics of tweaking the module to your liking, you might want to consider uploading those changes to our GitHub repository, so that they can be shared with other Gibbon users who might need them. Good luck!