FamilySearch has an index to Kentucky Marriages. Willie H. Roberts married Cora Smith, 22 February 1912, Laurel County, KY. The parents of both parties are given.
You can get an actual copy of the marriage record from the County Clerk in Laurel Co. Call them and ask how much it is for an UNCERTIFIED PHOTOCOPY of the record they have. Most KY counties charge a dollar or so. Send your written request, with the cash and an SASE.
PS: There are lots of other records for this family, including marriages of some of the children in Indiana. I suggest you mine FamilySearch.org for this bunch. If you haven't used this site before, you are missing a lot of FREE records.