I have tried to create a sequence in SQL Server 2008 using the following query,
CREATE SEQUENCE serial START 100
I got the following syntax
You just cannot do this.
SQL Server 2008 does not have the concept of a SEQUENCE - this is a new feature in SQL Server 2012 (MSDN documentation here).
Typically, you want to create an "auto-increasing" column for your table - in that case, use the IDENTITY column attribute instead:
CREATE TABLE dbo.YourTable
( TableID INT IDENTITY,
.....