How was cobalt made?

It's not actually "made". It's a raw element in the periodic table. It was "found" in 1938 by Seaborg and Livingood, but Cobalt has been used throughout all history.

answ2. Cobalt is made in the heart of a star by a process named nucleosynthesis, as part of a silicon burning reaction. Nickel and iron are other elements which take part in the same reaction. But that's pretty advanced stuff.

Sufficient for you to know that the elements in your body were once part of a star!