I cant aply textures to my imported blender files

Hi
I am a newbie and ive seen a few tutorials of how to aply textures to an imported file from blender.
I export it as a fbx file and when i go to unity a try to aply a texture that previously i have imported as a asset, but when i apply to my object it doesnt work.
However if i apply the texture to game object cteated in unity ( a plane, a cube, whatever…) everything is fine.

So my problem should be in my blender file

Anybody can help me.
I have the lastest version of both software.
Thanks

You need to UV map your models. Also you can just save as .blend, no need to manually export.