Use first and last name instead of username in post

Currently, when you publish a new post, in the latest news section, it shows the published name as the username and in my case, it says “admin”. How do i get it to use my first and last name in each section? Or what code do i need to edit?
You can see what i mean by going to the site if you don’t understand: delgame.com

In some areas it uses my first and last name under the post and in other areas, it uses the username.