Registration form layout, 2 fields on 1 line

Hi, I have searched the form for various answers on how to have 2 fields on the one line on the registration form. I found this solution at www.joomlapolis.com/documentation/279-community-builder/tutorials/18353-using-substitutions-throughout-cb but unfortunately I have not been able to follow the instructions and make it happen.
Basically I want to have the field Firstname and then Lastname on one line.
Is anybody able to provide specific instructions on how to make this happen?
Thanks, JR

I should add, I have created a custom html field and tried various substitutions but no success.
I also saw in another post, adding this CSS but where exactly should it be added?
#cbfr_46,
#cbfr_48 {
display: inline-block;
width: 50%;
}

Recommend just not using two fields. Set "Name Style" to Single Name Field in CB configuration. Otherwise your only option is to use CSS since you need this to apply to registration.

Thanks for your reply but your suggestion to set name style to single is not valid for what I have to do. It's a membership application form and I have many different fields that should shared on one line.
sbsc.net.au/index.php/membership/test-only
So back to my question, where exactly should this CSS be added? Is this the correct format for the CSS?
#cbfr_46,
#cbfr_48 {
display: inline-block;
width: 50%;
}

I have added it to the CSS Class in the Global field setup but that has no effect.
Thanks for you help.
JR

See the below on how to add CSS overrides to CB.

www.joomlapolis.com/blog/kyle/18711-template-css-overrides-made-easy

I can't help you with your CSS. We do not provide custom coding assistance. We only provide simple code examples, which is a benefit exclusively for subscribers.