Leif Erikson (or Leifur Eiríksson) was born in Iceland in 970 and died in 1020. He was son of Eric the Red who lived on the West Coast of Greenland and was an outlaw from Norway. Leif's friend, Lars Almvig, told a saga of a land far to the west that had been seen through a mist by a Viking band led by Bjarni Herjulfsson in 986 that had been blown off course. Encouraged by the constant need of land to farm, Leif organized a voyage and bought Bjarni's ship and headed west in about A.D. 990. He followed Bjarni's route in reverse, making three landfalls after about 4 1/2 days.
The first of these he named Helluland or Flat-Stone Land which is now Labrador.
L'Anse aux Meadows
In 1960 a Norwegian explorer and writer, Helge Ingstad, came upon the site at L'Anse aux Meadows, Newfoundland, after being led there by a local inhabitant. Over the course of the next eight years, Ingstad, his wife, and an international team of archaeologists excavated the site and found the remains of eight Norse buildings from the 11th century. The walls and roofs had been of sod, laid over a supporting frame. The buildings were of the same kind as those used in Iceland and Greenland just before and after the year 1000. Long narrow fireplaces in the middle of the floor served for heating, lighting and cooking. Several artifacts of Norse origin were found as well.
Some of the artifacts were those used by Norse women, and along with the discovery of an iron forge, indicated that the site was used as a settlement for extended stays. Subsequent excavations by Parks Canada in the 1970's uncovered an iron smithy by the forge, and a building where timber was cut and prepared for transport as lumber. This corresponds to descriptions in the Nordic sagas of timber being prepared to take back to Greenland, which was a scarce and valuable resource there. 
Why this settlement was abandoned is not known, but one suggested reason was harassment from the native Americans, who outnumbered the settlers despite the fighting prowess of the Norse. Another explanation is economic - while the region offered valuable resources, in practical terms Europe was as close as Vinland and had more to offer.
Conversion to Christianity
According to the available documentary source, the Nordic sagas, Erikson was a Christian convert, and spread his new religion to his colonies. His conversion took place during a visit to Norway in 999 A.D., where he was converted by King Olaf I, and instructed to carry the faith to Greenland. 
Return to Greenland
Leif returned to Greenland in 1001. Leif never returned and attempts at settlement of Vinland were unsuccessful due to the native North Americans.
(Excerpted for "Norwegian Explorers on the ODIN website, produced for the Norwegian Ministry of Foreign Affairs.) Compton's Interactive Encyclopedia, 1995 ed. "Leif Ericson."
- Saga of Erik the Red, chapter 4
- http://www.bartleby.com/65/le/LeifEric.html The Columbia Encyclopedia, Sixth Edition. 2001-07