Generate sql: Formula Field in SQL Server 2000

Does anyone know how to use Formula Field in SQL Server 2000. I have googled a lot, but haven't been able to find out how to use it..

Thxyou can add/subtract or write a formula to compute from values in other columns..
lets say you have colA, colB and colC. In colC, you can set the formula as colA+ColB.

you can look for "computed columns" in BOL.