Pass logged in users info to form fields

Hi,
I am currently using cms Builder with the membership plugin installed and everything is working well. I have a login protected area that has a form in it and I would like to pre-populate some of the form fields with the current logged in users info ex. name, apartment number, phone number and email. I'm not to sure where to start.

I am using Machform to create the forms and do know that I have to pass the variables through the browser's address bar or something but I'm not quite sure. I'm not an idiot at this, I'm just a little unfamiliar. Any help would be great. Thanks.