Looking to add a search widget on my header image

Hope someone can help, I am still playing around with some themes but came around to this one, it seems like it may work.

I am still quite new to coding, etc. and need some help doing something I have not been able to get right at all.

I am trying to add a widget (simple search) of mine into the header background image of the site. Can anyone help with coding and where would I put it?

I currently have my search function placed in a widget (Custom Widget Area Plugin) and have the piece of code, I just dont know how to get it into the header background image along with a border with a slightly see-through background…

Again, I am new to this and to support forums so…please be patient ??