Create a geography/geometry column from x and y fields - SQL Server 2008

I'm new in SQL Server 2008 and I hope you will understand my question/need.

Thus, I have a table which contains 3 fields (Name, Lat and Long) in my data base (spatial). I want to create a geometry/geography column based on those fields (Lat and Long) but unfortunately without any success.

My question is: How can I manage to do that?