I am designing a copper top of a flag post.
How do i make the surface texture reflective, so that it can reflect every object and light in the environment?
Enable cycles render and add a new Principled BSDF material for your object.
Set metallic to 1.
There are two selection boxes to set to make reflection available. I'll show this on Blender 2.79
Properties -> Scene -> Shading -> Ray Tracing should be enabled.
Properties -> FlagPostTopObject -> Material -> Surface -> Shading
should have some value, or else you don't get the
Properties -> FlagPostTopObject -> Material -> Surface -> Mirror
pane on a fresh install of Blender.
Properties -> FlagPostTopObject -> Surface -> Mirror should be enabled.
You can pick the color to reflect. To make the surface fully reflective you set the Reflectivity to one. Depth is the maximum number of times a ray is reflected, if you have for example two mirrors facing each other. The reflection of light that the Fresnel equations predict is known as Fresnel reflection, but the zero you see in my screenshot next to Fresnel, is no physical constant. You can set it to two and the reflection diminishes. To make the material look like copper, you will have to experiment a little.