Help adding new objects into my project

Hello,
I have project (3d project) and when I transfer objects that people here posted into my folder, the items are put with no colors at all, I tried to do stuff with adding textures and etc but it doesn’t come to it’s normal color.

Could anyone please point me to a guide or explain me how to do it?
Thank you.

Hi can you post a screenshot demonstrating the issue you are having.