Add another Style sheet to WordPress Blog

Ok well Im somewhat new to wordpress, but here is what Im trying to do. I am trying to add a google search bar to my website (not a google search that searches my site, but the actual google search that searches the web). Basically I want to add the google search bar here, to my header on my wordpress blog. Any help would be greatly appreciated.

To some up, how can I add the website below to my header?
https://go.infinise.com/