1. In Object Explorer, right-click the table to which they want to add columns and choose Design (Modify in SP1 or earlier).
Table Designer opens with the cursor placed in the first blank cell in the Column Name column. They can also right-click a row in the table and select Insert Column from the shortcut menu. A blank column row is inserted.
2. In the Column Name column, type the column name in the cell. The column name is a required value.
3. Press the TAB key to go to the Data Type cell and select a data type from the dropdown. This too is a required value, and will be assigned the default value if they don’t choose one.
4. Continue to define any other column properties in the Column Properties tab.