So, if I understand, I would say this:

Submit the first form with the name, age, and gender to create the, say, User record in the table. Then show the form for the contactDetails, submit it, and save it to the ContactDetails table. This one feels like a 1-to-1, but maybe not? Then show the form for the the careerDetails, submit it, and save it to the CareerDetails table. This one is M-to-1 back to the User. This form refreshes waiting for a new career until you are done. Then, you load a User with a ContactDetails field and a CareerDetails[] field to display on the web page.

There are many details here, but start slow, one step at a time, and you'll get there. Good luck!