How to create the new form fields for specific requirement ?

Lakshmana, not sure what you're referring to?
 

What is the requirement? Are you trying to create new fields in Marketo or just add fields to a form?

Same question, you want to create a new field?

Do a search for "create new field in marketo" and you'll find what you need.
 

Admin>Field Management>New
if this is a Marketo only field, that's ok. If you need Salesforce to see it, you should create it in SFDC first.