What to do if i just found out today that one of our employees has hepatitis c. how contageous is it?

Not contagious unles: Hepatitis c is not contagious unless you come in contact with that person and their blood or use IV drugs (sharing needles with them), sexually, sharing razors, etc with them. It is not passed through kissing or using the same bathroom or touching. There is no indication to distance yourself from the employee, and now a days there are excellent treatments available.