Home page search boxes – resize + position?

Hi
I’m new to this and setting up my first site with Premiumpress and could really do with a little help with what are probably straightforward (hopefully) questions…

– I can’t seem to resize the search boxes on the home page. They are full width, but I’d like them side by side… is this possible? I’ve seen it in some of the child themes, but no matter what child theme I use, it always appears full width for me. What do I need to do to make this change?
– I’d like the search boxes to overlay over a background image on the home page and not sit above or below it. What do I need to do to achieve this?

Your guidance would be must appreciated.
Thanks!