Save text info

I have an html page with <input type="text"> text sections.  This is for the user to store his\her emergency information incase of an emergency.  This also allows the client to input items like certification numbers, medications they might be taking, etc.. general user information that our clientele seems to forget or could be provided to a doctor in the case of an accident.

I would like to be able to store this information in a simple text file so after the user inputs the information and update it as needed.