CPT Templates


I don’t know if I am on the right forum, but here is my question anyway.
I set a cpt to my website, but the editor for these custom posts is different from the theme’s post editor, so my custom posts look different from the default’s theme posts, because it’s not possible to stylish them with the same layout options (mastheader, sidebar…).
As I’m not a developer, I searched for some tutorial to help on assign the default theme’s template to the cpt, but I couldn’t find a solution.
Any guidance on this?
Thanks for any help.