Add Custom Field With Password How To Do?

[domaingood]

Name  Type Required Visible to Clients Read Only for Clients
I want set Expression Validation like wanna customer can have to choose security Pin between 4 and and 6 and only latter.and when use it will show *****

/^([a-zA-Z0-9_-])+(\.[a-zA-Z0-9_-]+)*\.([a-zA-Z]{2,6})$/

A username between 4 and 28 characters in length, alpha-numeric, and allowing underscores

/^[a-z\d_]{4,28}$/i

A telephone number in the following format: (###) ###-####

/^(\(?[0-9]{3,3}\)?|[0-9]{3,3}[-. ]?)[ ][0-9]{3,3}[-. ]?[0-9]{4,4}$/

A date in the format DD/MM/YYYY

/^\d{1,2}\/\d{1,2}\/\d{4}$/

See http://www.regexpr.com/cheatsheet/ for a detailed guide

 

Thank you