Dear Mari
Welcome to Ireland Reaching Out!
As you can see from the link below, Derrylossary is a Civil Parish in Co. Wicklow:
http://www.irishtimes.com/ancestor/fuses/townlands/index.cfm?fuseaction=TownlandsInCivil&civilparishid=2671&civilparish=Derrylossary&citycounty=Wicklow
Records for the corresponding Roman Catholic Parish of Glendalough begin in 1897 for baptisms and 1808 for marriages. There are some missing dates too though; 1838-1839 for baptisms and 1838-1840 for marriages. If Ellen came from outside the parish they would have married elsewhere. As this is the case you could try checking the following:
www.familysearch.org has a huge database of genealogical records including some church records for Ireland.
www.rootsireland.ie have a large collection of Irish Church records, however you have to pay to use this site.
Other important sources include the Tithe Applotment Books and Griffith?s Valuation. Even though these sources only record the head of the household, the information is very important and can be valuable:
Tithe Applotment Books (1823-1837): http://titheapplotmentbooks.nationalarchives.ie/search/tab/index.jsp
Griffith?s Valuation (1847-1864): http://www.askaboutireland.ie/griffith-valuation/
The National Archives of Ireland: http://www.census.nationalarchives.ie/search/ you can search the 1901/1911 Census on the National Archives page too, for instances of the family name at that time
Remember to post any new information that you find here. The more information you post, the more likely it is that one of our volunteers will be able to advise or assist you. Also include information concerning which sources you may have already used so others may further your search.
Best of luck with your search
Clare Doyle
Genealogy Support