Almost anyone we find will be more advanced than us. In any case, to answer your question, you would not tell them anything until you knew something about them, until you knew what might make sense to tell them.
1564 - 1616
1803 – 1882
1854 – 1900
1942 – 2016
1928 – 2014
1835 – 1910
1869 – 1948
1884 – 1962
1898 – 1963
1929 – 1993
1879 – 1955
1809 – 1865