After you fill out Deceased ancestor's name, birth place and whether the search is with a relative etc you click on Search and a listing of possiblities come up.Then you click on the one that looks like it fits to what you know and a different page comes up with more details.
On the botton of it there is something like this:
CITING THIS RECORD
"United States Public Records, 1970-2009," database, FamilySearch(https://familysearch.org/ark:/61903/1:1:QJCR-3BNY : 23 May 2014), Dorothy Barry, Residence, Danbury, Connecticut, United States; a third party aggregator of publicly available information.
Just cut and paste Citing this record and the rest onto the source section of WikiTree.
*CITING THIS RECORD "United States Public Records, 1970-2009," database, FamilySearch(https://familysearch.org/ark:/61903/1:1:QJCR-3BNY : 23 May 2014), Dorothy Barry, Residence, Danbury, Connecticut, United States; a third party aggregator of publicly available information.
Then another person looking at your profile and sources section will be able to click on the URL which is in this case: https://familysearch.org/ark:/61903/1:1:QJCR-3BNY and see the information that is contained there.