Replacing line in database with new input info

Hi, I’m working on real estate agent directory. agent are members of the site, and when they log in they are directed to and update your info page (a form that connected to the database that connected to repeater than connected to their own dynamic page) long story short I am trying to find a tutorial that will show me how each time they are logged in new information that they will input will replace old info. please help :))

You will need to use a dataset in a read write mode, and set in to the item you wanna modify using dataset filter.