Where do I find the spacing between page content and header?

you will get more help if you post a URL

https://lexismemorylab.com/

Not clear from your wording what you want to do. If you mean put space under the header image before the widgets and contents start, its this CSS
line 178 in stylesheet

.content {
background:transparent url(images/content-tail.gif) repeat-x scroll 0 0;
clear:both;
padding:0 0 10px;  <----- change to   10px 0 10px   or  15px 0 10px
}

thx that helped loads!