how to dig a hole on a object? I simply want to dig a hole on a cube. I tried to extrude after creating a circle on the surface, which left me a hole with both ends covered by the original surfaces. I tried the Bridge Edge Loops and got the same result. I cannot find a way to get rid of the surface inside the circle(it cannot be seleted and delete).

I am a beginner hopefully anyone can help me.
thanks in advance.
Add a Cylinder and put to where you want to have your hole and how deep it shall be.
Add a "Boolean" modifier on the cube. In the settings set "Operation:" to Difference and the Cylinder as "object:"
Apply the modifier.