After the story of the akaida at the end of the last parsha, Avrohom realized that Yitzchak, who was 37 years old, should be getting married. At the very end of that parsha, in the maftir reading, some genealogy information was given including the birth of Rivkah, which was to be Yitzchak's future wife. So in this second aliyah, the Torah begins the story of Avrohom sending his servant Eliezer back to the land of Avrohom's birth to find a wife for Yitzchak.