How to I make changes to theme options possibilities?

Hello,

I managing a wordpress site and I need to add social options to a theme, the tricky things is that the user needs to be able to change the link and updated from the wp dashboard (under theme options).

The template allows to change and update facebook and youtube links located in the header, however I need to add pinterest and linkdin social.

I found a file called “social.php”, there I can add linkdin and pinterest, however the change there doesn’t appear in the “theme options”

I couldn’t find it in “functions.php” either, I’ve never written a template for wp, anyone knows how can I find the proper file?

Thanks!