Go to Sql Server Mgmt Studio.

Navigate to the table.

Right click --> Edit/Modify Table

DO NOT SAVE AFTER DOING BELOW CHANGES

Add New Column.

[ select identity,primary key, foreign key, etc....]

Right Click newly created column --> select Generate Change Script

Done.

A new dialogue box will appear goving you the script for all the changes done above.

Copy the script and use as required.

Verify the script provided by Microsoft and do necessary changes.