Profile Page Modification

Hello,
I wanted to modify The Profile Page a bit,
That is in the About Section of every User i wanted to add some header sections like

—–BASIC DETAILS—–
Below this section to display some fields such as Firstname Gender etc..

Simillary,
—–LOCATION DETAILS—-
In this section to display City, Country etc..

My Query is That in which exact php and css file to make changes, And also wanted to display Firstname value infront of it instead of displaying in next line.

Please help me with these two. ADDING A SECTION & DISPLAYING VALUES INFRONT OF FIELDS.

Thank You.