DNS Needs to be updated

hey! I’m a new user in wordpress, and I started of with onebeanblog.wordpress.com, after that, I purchased the domain marenostrum.com from another account because I just didn’t know what I was doing. I mapped it back to my original wordpress account for like $12, but when I make it primary domain and try to view the site, the webpage is just blank. Also when I go into the payment settings of the domain, it says “DNS needs to be updated”
I’m lost at this point, any help would be seriously appreciated. Thank you for your time.