celt0603,
I am not clear what information you already have and what you are seeking.
Have you searched the IGI on FamilySearch at:
http://www.familysearch.orgIt has the following records:
William KINCAID and Mary LONG had:
*A daughter (unnamed) b 2 Feb 1864, 0148 Glendermot, Londonderry, Ireland
*Margaret b 4 Nov 1865, Port Glasgow, Renfrewshire, Scotland
*Mary b 25 Nov 1867, Port Glasgow, Renfrewshire, Scotland (mother's name as LANG)
*William b 8 Mar 1871, Port Glasgow, Renfrewshire, Scotland
So you now know where William and Mary came from in Ireland - or at least where they were before they moved to Scotland.
Have you searched on (the pay per view site) ScotlandsPeople at:
http://www.scotlandspeople.gov.ukScotlandsPeople has online BDM records and also the 1861, 1871, 1881, 1891 and 1901 censuses.
The census records should give a birthplace for your ancestors - however, often this is merely stated as 'Ireland'. But you could be lucky and get a more precise birthplace in one or more of the censuses.
Scottish death certificates list (if known by the informant) the name and occupation of the father of the deceased, and name and maiden surname of the mother of the deceased. So if you can find the deaths of your ancestors, you will very likely get back another generation.
So there is plenty of information available for you to research.
Good luck,
JAP