Assuming you live in the UK and have access to a library you should be able to find the parents using the information in the marriage certificate (1857 Manchester). This should give the name of the father and the 1851 census should be on-line in the library so it shouldn't be too difficult to find William and his parents in either the 1851 and/or the 1841 census. William was Manchester born and the 1861 census should lead you to where Catharine was born and her parents.