You can do it by an edit of table design if you want
do it with query see following.
Syntax:
ALTER TABLE {TABLENAME}
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL}
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
[WITH VALUES]
Note: Use WITH VALUES to update existing null-able
rows.
Example:
ALTER TABLE MyTable
ADD MyTableTypeID INT NOT NULL
CONSTRAINT Constraint_MyTableTypeID DEFAULT 0
GO
Note: WITH VALUES handles the NOT NULL part
ALTER TABLE MyTable
ADD MyTableTypeID INT
CONSTRAINT Constraint_MyTableTypeID DEFAULT 0 WITH VALUE
GO