If you using template which support visual search form builder like:
Property Listing and Hotel Booking Portal #02
Real Estate Retro Template #03
Horse Market Sell & Rent Portal
You can customize forms by guide:
http://geniuscript.com/wbooking/user_guide_theme/#!/custom_search_form
But if you wish for example split row into 3 columns or add custom css class then you can add it also:
then depend on bootstrap version or custom classes you can add for example “bootstrap3″:
More detail about bootstrap grid system:
http://www.w3schools.com/bootstrap/bootstrap_grid_examples.asp