Edit wordpress template / edit plugins

My site has a few widgets that show related posts on the sidebar and below article, I want to edit those widgets to only show certain type of posts, lets call it NATIVE posts. So I'd also like for you to create a tab on wordpress (via plugin or manually) that we can only manage these native posts. Basically will be a thumbnail and title only. Need it asap, and I believe it won't take long to do it. People only, do not contact if you're an agency.