Customize wordpress theme

I need someone to do a simple child theme for this theme at [login to view URL] you can check out their user and admin demo for free to have a better idea, basically I just want the current adv submission using a single form layout to change into individual form submission for different category select, so that I can have different fields appear for different forms. Etc. currently the theme is using one form for all adv submission regardless which category you wanna place the adv, but I want to be able to create different forms for adv place in different category with the field I wants.