This FamilySearch site has a great deal of information on our family genealogy and it goes back hundreds of years.
To pull up the longest line of our family click on this link (or cut and paste it into your browser as listed below) and enter “Edmund Pendleton” under first name then “Cohill” for last name. You do not need to fill out the rest. Press enter and select him from the other people listed.
http://www.familysearch.org/Eng/Search/frameset_search.asp
Once you click the search, then you should see "Edmund Pendleton COHILL" Ancestral File Gender: M Birth/Christening: 3 Dec 1855 Elmira, Chemung, Ny, as the first item on the listing. Then you click on his name to provide you with his "Individual Record". Then you can click on the "Pedigree" to view the family tree or "Family" to view "Family Group Record".
Once you view these records, you can also load this information on your PC clicking on the "Download GEDCOM". Once Download this information can be loaded into Genealogical Software program like Family Tree Maker: http://www.familytreemaker.com/.
You can view some of the Cohill information that has been download and put into Family Tree Maker by viewing this site.