var first_name = $('input[name=first_name]').val();
    var last_name = $('input[name=last_name]').val();

    if (first_name==""){
        $('input[name=first_name]').css({'border':'2px solid red'});
        proceed = false;
        }
    if (last_name==""){
        $('input[name=last_name]').css({'border':'2px solid red'});
        proceed = false;
        }

$(document).ready(function(){

    $('#YOUR_FIELD_ID_c').val("Some value");

});