Why not start by telling this list the names of your ancestors? List those who emigrated, with approximate dates and places known in the US. Coincidences might occur, if you give them a specific nudge.
Most amateur genealogists are generous-- if you indicate you will also freely share. One of us may not have your exact family, but might know which library or source or organization is most likely to provide a shortcut for you.
Best of luck, Barb