@Cadmon You cannot change nameservers on a domain registered through Cloudflare. You need to get the website ip address from the website settings in siteground and create an A recordA record in Cloudflare that points to that ip address.
thanks I figured it out "how to point to the dns" make a dns record = A type then enter the ip address of the host (if you can't find it call/contact them) depending on who you're with leave it unproxied ttl depends on who you are with as well (1-2 hrs or couple minutes)